Add m-esr52 at 52.6.0

53 files changed, 5129 insertions, 0 deletions

diff --git a/toolkit/components/osfile/tests/mochi/.eslintrc.js b/toolkit/components/osfile/tests/mochi/.eslintrc.js
new file mode 100644
index 000000000..8c0f4f574
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/.eslintrc.js
@@ -0,0 +1,7 @@
+"use strict";
+
+module.exports = {
+  "extends": [
+    "../../../../../testing/mochitest/chrome.eslintrc.js"
+  ]
+};
diff --git a/toolkit/components/osfile/tests/mochi/chrome.ini b/toolkit/components/osfile/tests/mochi/chrome.ini
new file mode 100644
index 000000000..1da463316
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/chrome.ini
@@ -0,0 +1,15 @@
+[DEFAULT]
+skip-if = os == 'android'
+support-files =
+  main_test_osfile_async.js
+  worker_handler.js
+  worker_test_osfile_comms.js
+  worker_test_osfile_front.js
+  worker_test_osfile_shared.js
+  worker_test_osfile_unix.js
+  worker_test_osfile_win.js
+
+[test_osfile_async.xul]
+[test_osfile_back.xul]
+[test_osfile_comms.xul]
+[test_osfile_front.xul]
diff --git a/toolkit/components/osfile/tests/mochi/main_test_osfile_async.js b/toolkit/components/osfile/tests/mochi/main_test_osfile_async.js
new file mode 100644
index 000000000..b940a032a
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/main_test_osfile_async.js
@@ -0,0 +1,443 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Promise.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+Components.utils.import("resource://gre/modules/AsyncShutdown.jsm");
+
+// The following are used to compare against a well-tested reference
+// implementation of file I/O.
+Components.utils.import("resource://gre/modules/NetUtil.jsm");
+Components.utils.import("resource://gre/modules/FileUtils.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+var myok = ok;
+var myis = is;
+var myinfo = info;
+var myisnot = isnot;
+
+var isPromise = function ispromise(value) {
+  return value != null && typeof value == "object" && "then" in value;
+};
+
+var maketest = function(prefix, test) {
+  let utils = {
+    ok: function ok(t, m) {
+      myok(t, prefix + ": " + m);
+    },
+    is: function is(l, r, m) {
+      myis(l, r, prefix + ": " + m);
+    },
+    isnot: function isnot(l, r, m) {
+      myisnot(l, r, prefix + ": " + m);
+    },
+    info: function info(m) {
+      myinfo(prefix + ": " + m);
+    },
+    fail: function fail(m) {
+      utils.ok(false, m);
+    },
+    okpromise: function okpromise(t, m) {
+      return t.then(
+        function onSuccess() {
+          util.ok(true, m);
+        },
+        function onFailure() {
+          util.ok(false, m);
+        }
+      );
+    }
+  };
+  return function runtest() {
+    utils.info("Entering");
+    try {
+      let result = test.call(this, utils);
+      if (!isPromise(result)) {
+        throw new TypeError("The test did not return a promise");
+      }
+      utils.info("This was a promise");
+      // The test returns a promise
+      result = result.then(function test_complete() {
+        utils.info("Complete");
+      }, function catch_uncaught_errors(err) {
+        utils.fail("Uncaught error " + err);
+        if (err && typeof err == "object" && "message" in err) {
+          utils.fail("(" + err.message + ")");
+        }
+        if (err && typeof err == "object" && "stack" in err) {
+          utils.fail("at " + err.stack);
+        }
+      });
+      return result;
+    } catch (x) {
+      utils.fail("Error " + x + " at " + x.stack);
+      return null;
+    }
+  };
+};
+
+/**
+ * Fetch asynchronously the contents of a file using xpcom.
+ *
+ * Used for comparing xpcom-based results to os.file-based results.
+ *
+ * @param {string} path The _absolute_ path to the file.
+ * @return {promise}
+ * @resolves {string} The contents of the file.
+ */
+var reference_fetch_file = function reference_fetch_file(path, test) {
+  test.info("Fetching file " + path);
+  let promise = Promise.defer();
+  let file = new FileUtils.File(path);
+  NetUtil.asyncFetch({
+    uri: NetUtil.newURI(file),
+    loadUsingSystemPrincipal: true
+  }, function(stream, status) {
+      if (!Components.isSuccessCode(status)) {
+        promise.reject(status);
+        return;
+      }
+      let result, reject;
+      try {
+        result = NetUtil.readInputStreamToString(stream, stream.available());
+      } catch (x) {
+        reject = x;
+      }
+      stream.close();
+      if (reject) {
+        promise.reject(reject);
+      } else {
+        promise.resolve(result);
+      }
+    });
+
+  return promise.promise;
+};
+
+/**
+ * Compare asynchronously the contents two files using xpcom.
+ *
+ * Used for comparing xpcom-based results to os.file-based results.
+ *
+ * @param {string} a The _absolute_ path to the first file.
+ * @param {string} b The _absolute_ path to the second file.
+ *
+ * @resolves {null}
+ */
+var reference_compare_files = function reference_compare_files(a, b, test) {
+  test.info("Comparing files " + a + " and " + b);
+  let a_contents = yield reference_fetch_file(a, test);
+  let b_contents = yield reference_fetch_file(b, test);
+  is(a_contents, b_contents, "Contents of files " + a + " and " + b + " match");
+};
+
+var reference_dir_contents = function reference_dir_contents(path) {
+  let result = [];
+  let entries = new FileUtils.File(path).directoryEntries;
+  while (entries.hasMoreElements()) {
+    let entry = entries.getNext().QueryInterface(Components.interfaces.nsILocalFile);
+    result.push(entry.path);
+  }
+  return result;
+};
+
+// Set/Unset OS.Shared.DEBUG, OS.Shared.TEST and a console listener.
+function toggleDebugTest (pref, consoleListener) {
+  Services.prefs.setBoolPref("toolkit.osfile.log", pref);
+  Services.prefs.setBoolPref("toolkit.osfile.log.redirect", pref);
+  Services.console[pref ? "registerListener" : "unregisterListener"](
+    consoleListener);
+}
+
+var test = maketest("Main", function main(test) {
+  return Task.spawn(function() {
+    SimpleTest.waitForExplicitFinish();
+    yield test_stat();
+    yield test_debug();
+    yield test_info_features_detect();
+    yield test_position();
+    yield test_iter();
+    yield test_exists();
+    yield test_debug_test();
+    info("Test is over");
+    SimpleTest.finish();
+  });
+});
+
+/**
+ * A file that we know exists and that can be used for reading.
+ */
+var EXISTING_FILE = OS.Path.join("chrome", "toolkit", "components",
+  "osfile", "tests", "mochi", "main_test_osfile_async.js");
+
+/**
+ * Test OS.File.stat and OS.File.prototype.stat
+ */
+var test_stat = maketest("stat", function stat(test) {
+  return Task.spawn(function() {
+    // Open a file and stat it
+    let file = yield OS.File.open(EXISTING_FILE);
+    let stat1;
+
+    try {
+      test.info("Stating file");
+      stat1 = yield file.stat();
+      test.ok(true, "stat has worked " + stat1);
+      test.ok(stat1, "stat is not empty");
+    } finally {
+      yield file.close();
+    }
+
+    // Stat the same file without opening it
+    test.info("Stating a file without opening it");
+    let stat2 = yield OS.File.stat(EXISTING_FILE);
+    test.ok(true, "stat 2 has worked " + stat2);
+    test.ok(stat2, "stat 2 is not empty");
+    for (let key in stat2) {
+      test.is("" + stat1[key], "" + stat2[key], "Stat field " + key + "is the same");
+    }
+  });
+});
+
+/**
+ * Test feature detection using OS.File.Info.prototype on main thread
+ */
+var test_info_features_detect = maketest("features_detect", function features_detect(test) {
+  return Task.spawn(function() {
+    if (OS.Constants.Win) {
+      // see if winBirthDate is defined
+      if ("winBirthDate" in OS.File.Info.prototype) {
+        test.ok(true, "winBirthDate is defined");
+      } else {
+        test.fail("winBirthDate not defined though we are under Windows");
+      }
+    } else if (OS.Constants.libc) {
+      // see if unixGroup is defined
+      if ("unixGroup" in OS.File.Info.prototype) {
+        test.ok(true, "unixGroup is defined");
+      } else {
+        test.fail("unixGroup is not defined though we are under Unix");
+      }
+    }
+  });
+});
+
+/**
+ * Test file.{getPosition, setPosition}
+ */
+var test_position = maketest("position", function position(test) {
+  return Task.spawn(function() {
+    let file = yield OS.File.open(EXISTING_FILE);
+
+    try {
+      let view = yield file.read();
+      test.info("First batch of content read");
+      let CHUNK_SIZE = 178;// An arbitrary number of bytes to read from the file
+      let pos = yield file.getPosition();
+      test.info("Obtained position");
+      test.is(pos, view.byteLength, "getPosition returned the end of the file");
+      pos = yield file.setPosition(-CHUNK_SIZE, OS.File.POS_END);
+      test.info("Changed position");
+      test.is(pos, view.byteLength - CHUNK_SIZE, "setPosition returned the correct position");
+
+      let view2 = yield file.read();
+      test.info("Read the end of the file");
+      for (let i = 0; i < CHUNK_SIZE; ++i) {
+        if (view2[i] != view[i + view.byteLength - CHUNK_SIZE]) {
+          test.is(view2[i], view[i], "setPosition put us in the right position");
+        }
+      }
+    } finally {
+      yield file.close();
+    }
+  });
+});
+
+/**
+ * Test OS.File.prototype.{DirectoryIterator}
+ */
+var test_iter = maketest("iter", function iter(test) {
+  return Task.spawn(function() {
+    let currentDir = yield OS.File.getCurrentDirectory();
+
+    // Trivial walks through the directory
+    test.info("Preparing iteration");
+    let iterator = new OS.File.DirectoryIterator(currentDir);
+    let temporary_file_name = OS.Path.join(currentDir, "empty-temporary-file.tmp");
+    try {
+      yield OS.File.remove(temporary_file_name);
+    } catch (err) {
+      // Ignore errors removing file
+    }
+    let allFiles1 = yield iterator.nextBatch();
+    test.info("Obtained all files through nextBatch");
+    test.isnot(allFiles1.length, 0, "There is at least one file");
+    test.isnot(allFiles1[0].path, null, "Files have a path");
+
+    // Ensure that we have the same entries with |reference_dir_contents|
+    let referenceEntries = new Set();
+    for (let entry of reference_dir_contents(currentDir)) {
+      referenceEntries.add(entry);
+    }
+    test.is(referenceEntries.size, allFiles1.length, "All the entries in the directory have been listed");
+    for (let entry of allFiles1) {
+      test.ok(referenceEntries.has(entry.path), "File " + entry.path + " effectively exists");
+      // Ensure that we have correct isDir and isSymLink
+      // Current directory is {objdir}/_tests/testing/mochitest/, assume it has some dirs and symlinks.
+      var f = new FileUtils.File(entry.path);
+      test.is(entry.isDir, f.isDirectory(), "Get file " + entry.path + " isDir correctly");
+      test.is(entry.isSymLink, f.isSymlink(), "Get file " + entry.path + " isSymLink correctly");
+    }
+
+    yield iterator.close();
+    test.info("Closed iterator");
+
+    test.info("Double closing DirectoryIterator");
+    iterator = new OS.File.DirectoryIterator(currentDir);
+    yield iterator.close();
+    yield iterator.close(); //double closing |DirectoryIterator|
+    test.ok(true, "|DirectoryIterator| was closed twice successfully");
+
+    let allFiles2 = [];
+    let i = 0;
+    iterator = new OS.File.DirectoryIterator(currentDir);
+    yield iterator.forEach(function(entry, index) {
+      test.is(i++, index, "Getting the correct index");
+      allFiles2.push(entry);
+    });
+    test.info("Obtained all files through forEach");
+    is(allFiles1.length, allFiles2.length, "Both runs returned the same number of files");
+    for (let i = 0; i < allFiles1.length; ++i) {
+      if (allFiles1[i].path != allFiles2[i].path) {
+        test.is(allFiles1[i].path, allFiles2[i].path, "Both runs return the same files");
+        break;
+      }
+    }
+
+    // Testing batch iteration + whether an iteration can be stopped early
+    let BATCH_LENGTH = 10;
+    test.info("Getting some files through nextBatch");
+    yield iterator.close();
+
+    iterator = new OS.File.DirectoryIterator(currentDir);
+    let someFiles1 = yield iterator.nextBatch(BATCH_LENGTH);
+    let someFiles2 = yield iterator.nextBatch(BATCH_LENGTH);
+    yield iterator.close();
+
+    iterator = new OS.File.DirectoryIterator(currentDir);
+    yield iterator.forEach(function cb(entry, index, iterator) {
+      if (index < BATCH_LENGTH) {
+        test.is(entry.path, someFiles1[index].path, "Both runs return the same files (part 1)");
+      } else if (index < 2*BATCH_LENGTH) {
+        test.is(entry.path, someFiles2[index - BATCH_LENGTH].path, "Both runs return the same files (part 2)");
+      } else if (index == 2 * BATCH_LENGTH) {
+        test.info("Attempting to stop asynchronous forEach");
+        return iterator.close();
+      } else {
+        test.fail("Can we stop an asynchronous forEach? " + index);
+      }
+      return null;
+    });
+    yield iterator.close();
+
+    // Ensuring that we find new files if they appear
+    let file = yield OS.File.open(temporary_file_name, { write: true } );
+    file.close();
+    iterator = new OS.File.DirectoryIterator(currentDir);
+    try {
+      let files = yield iterator.nextBatch();
+      is(files.length, allFiles1.length + 1, "The directory iterator has noticed the new file");
+      let exists = yield iterator.exists();
+      test.ok(exists, "After nextBatch, iterator detects that the directory exists");
+    } finally {
+      yield iterator.close();
+    }
+
+    // Ensuring that opening a non-existing directory fails consistently
+    // once iteration starts.
+    try {
+      iterator = null;
+      iterator = new OS.File.DirectoryIterator("/I do not exist");
+      let exists = yield iterator.exists();
+      test.ok(!exists, "Before any iteration, iterator detects that the directory doesn't exist");
+      let exn = null;
+      try {
+        yield iterator.next();
+      } catch (ex if ex instanceof OS.File.Error && ex.becauseNoSuchFile) {
+        exn = ex;
+        let exists = yield iterator.exists();
+        test.ok(!exists, "After one iteration, iterator detects that the directory doesn't exist");
+      }
+      test.ok(exn, "Iterating through a directory that does not exist has failed with becauseNoSuchFile");
+    } finally {
+      if (iterator) {
+        iterator.close();
+      }
+    }
+    test.ok(!!iterator, "The directory iterator for a non-existing directory was correctly created");
+  });
+});
+
+/**
+ * Test OS.File.prototype.{exists}
+ */
+var test_exists = maketest("exists", function exists(test) {
+  return Task.spawn(function() {
+    let fileExists = yield OS.File.exists(EXISTING_FILE);
+    test.ok(fileExists, "file exists");
+    fileExists = yield OS.File.exists(EXISTING_FILE + ".tmp");
+    test.ok(!fileExists, "file does not exists");
+  });
+});
+
+/**
+ * Test changes to OS.Shared.DEBUG flag.
+ */
+var test_debug = maketest("debug", function debug(test) {
+  return Task.spawn(function() {
+    function testSetDebugPref (pref) {
+      try {
+        Services.prefs.setBoolPref("toolkit.osfile.log", pref);
+      } catch (x) {
+        test.fail("Setting OS.Shared.DEBUG to " + pref +
+          " should not cause error.");
+      } finally {
+        test.is(OS.Shared.DEBUG, pref, "OS.Shared.DEBUG is set correctly.");
+      }
+    }
+    testSetDebugPref(true);
+    let workerDEBUG = yield OS.File.GET_DEBUG();
+    test.is(workerDEBUG, true, "Worker's DEBUG is set.");
+    testSetDebugPref(false);
+    workerDEBUG = yield OS.File.GET_DEBUG();
+    test.is(workerDEBUG, false, "Worker's DEBUG is unset.");
+  });
+});
+
+/**
+ * Test logging in the main thread with set OS.Shared.DEBUG and
+ * OS.Shared.TEST flags.
+ */
+var test_debug_test = maketest("debug_test", function debug_test(test) {
+  return Task.spawn(function () {
+    // Create a console listener.
+    let consoleListener = {
+      observe: function (aMessage) {
+        // Ignore unexpected messages.
+        if (!(aMessage instanceof Components.interfaces.nsIConsoleMessage)) {
+          return;
+        }
+        if (aMessage.message.indexOf("TEST OS") < 0) {
+          return;
+        }
+        test.ok(true, "DEBUG TEST messages are logged correctly.");
+      }
+    };
+    toggleDebugTest(true, consoleListener);
+    // Execution of OS.File.exist method will trigger OS.File.LOG several times.
+    let fileExists = yield OS.File.exists(EXISTING_FILE);
+    toggleDebugTest(false, consoleListener);
+  });
+});
+
+
diff --git a/toolkit/components/osfile/tests/mochi/test_osfile_async.xul b/toolkit/components/osfile/tests/mochi/test_osfile_async.xul
new file mode 100644
index 000000000..1ef103f02
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/test_osfile_async.xul
@@ -0,0 +1,23 @@
+<?xml version="1.0"?>
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<window title="Testing async I/O with OS.File"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="test();">
+
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+  <script type="application/javascript"
+          src="main_test_osfile_async.js"/>
+
+  <body xmlns="http://www.w3.org/1999/xhtml">
+    <p id="display"></p>
+    <div id="content" style="display:none;"></div>
+    <pre id="test"></pre>
+  </body>
+  <label id="test-result"/>
+</window>
diff --git a/toolkit/components/osfile/tests/mochi/test_osfile_back.xul b/toolkit/components/osfile/tests/mochi/test_osfile_back.xul
new file mode 100644
index 000000000..b6af6303f
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/test_osfile_back.xul
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<window title="Testing OS.File on a chrome worker thread"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="test();">
+
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+  <script type="application/javascript"
+          src="worker_handler.js"/>
+  <script type="application/javascript">
+  <![CDATA[
+
+let worker;
+
+function test() {
+  ok(true, "test_osfile.xul: Starting test");
+  if (navigator.platform.indexOf("Win") != -1) {
+    ok(true, "test_osfile.xul: Using Windows test suite");
+    worker = new ChromeWorker("worker_test_osfile_win.js");
+  } else {
+    ok(true, "test_osfile.xul: Using Unix test suite");
+    worker = new ChromeWorker("worker_test_osfile_unix.js");
+  }
+  SimpleTest.waitForExplicitFinish();
+  ok(true, "test_osfile.xul: Chrome worker created");
+  dump("MAIN: go\n");
+  worker_handler(worker);
+  worker.postMessage(0);
+  ok(true, "test_osfile.xul: Test in progress");
+};
+]]>
+  </script>
+
+  <body xmlns="http://www.w3.org/1999/xhtml">
+    <p id="display"></p>
+    <div id="content" style="display:none;"></div>
+    <pre id="test"></pre>
+  </body>
+  <label id="test-result"/>
+</window>
diff --git a/toolkit/components/osfile/tests/mochi/test_osfile_comms.xul b/toolkit/components/osfile/tests/mochi/test_osfile_comms.xul
new file mode 100644
index 000000000..88e474ce2
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/test_osfile_comms.xul
@@ -0,0 +1,84 @@
+<?xml version="1.0"?>
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<window title="Testing OS.File on a chrome worker thread"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="test();">
+
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+  <script type="application/javascript">
+  <![CDATA[
+
+"use strict";
+
+let worker;
+
+let test = function test() {
+  SimpleTest.info("test_osfile_comms.xul: Starting test");
+  Components.utils.import("resource://gre/modules/ctypes.jsm");
+  Components.utils.import("resource://gre/modules/osfile.jsm");
+  worker = new ChromeWorker("worker_test_osfile_comms.js");
+  SimpleTest.waitForExplicitFinish();
+  try {
+    worker.onerror = function onerror(error) {
+      SimpleTest.ok(false, "received error "+error);
+    }
+   worker.onmessage = function onmessage(msg) {
+    Components.utils.forceShrinkingGC();
+    switch (msg.data.kind) {
+      case "is":
+        SimpleTest.ok(msg.data.outcome, msg.data.description +
+        " ("+ msg.data.a + " ==? " + msg.data.b + ")" );
+        return;
+      case "isnot":
+        SimpleTest.ok(msg.data.outcome, msg.data.description +
+        " ("+ msg.data.a + " !=? " + msg.data.b + ")" );
+        return;
+      case "ok":
+        SimpleTest.ok(msg.data.condition, msg.data.description);
+        return;
+      case "info":
+        SimpleTest.info(msg.data.description);
+        return;
+      case "finish":
+        SimpleTest.finish();
+        return;
+      case "value":
+        SimpleTest.ok(true, "test_osfile_comms.xul: Received value " + JSON.stringify(msg.data.value));
+        let type = eval(msg.data.typename);
+        let check = eval(msg.data.check);
+        let value = msg.data.value;
+        let deserialized = type.fromMsg(value);
+        check(deserialized, "Main thread test: ");
+       return;
+      default:
+        SimpleTest.ok(false, "test_osfile_comms.xul: wrong message "+JSON.stringify(msg.data));
+        return;
+      }
+    };
+    worker.postMessage(0)
+    ok(true, "Worker launched");
+  } catch(x) {
+    // As we have set |waitForExplicitFinish|, we add this fallback
+    // in case of uncaught error, to ensure that the test does not
+    // just freeze.
+    ok(false, "Caught exception " + x + " at " + x.stack);
+    SimpleTest.finish();
+  }
+};
+
+]]>
+  </script>
+
+  <body xmlns="http://www.w3.org/1999/xhtml">
+    <p id="display"></p>
+    <div id="content" style="display:none;"></div>
+    <pre id="test"></pre>
+  </body>
+  <label id="test-result"/>
+</window>
diff --git a/toolkit/components/osfile/tests/mochi/test_osfile_front.xul b/toolkit/components/osfile/tests/mochi/test_osfile_front.xul
new file mode 100644
index 000000000..10d3fbd01
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/test_osfile_front.xul
@@ -0,0 +1,44 @@
+<?xml version="1.0"?>
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<window title="Testing OS.File on a chrome worker thread"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="test();">
+
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+  <script type="application/javascript"
+          src="worker_handler.js"/>
+  <script type="application/javascript">
+  <![CDATA[
+
+let worker;
+let main = this;
+
+function test() {
+  info("test_osfile_front.xul: Starting test");
+
+  // Test the OS.File worker
+
+  worker = new ChromeWorker("worker_test_osfile_front.js");
+  SimpleTest.waitForExplicitFinish();
+  info("test_osfile_front.xul: Chrome worker created");
+  dump("MAIN: go\n");
+  worker_handler(worker);
+  worker.postMessage(0);
+  ok(true, "test_osfile_front.xul: Test in progress");
+};
+]]>
+  </script>
+
+  <body xmlns="http://www.w3.org/1999/xhtml">
+    <p id="display"></p>
+    <div id="content" style="display:none;"></div>
+    <pre id="test"></pre>
+  </body>
+  <label id="test-result"/>
+</window>
diff --git a/toolkit/components/osfile/tests/mochi/worker_handler.js b/toolkit/components/osfile/tests/mochi/worker_handler.js
new file mode 100644
index 000000000..6c513e6ba
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/worker_handler.js
@@ -0,0 +1,34 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function worker_handler(worker) {
+  worker.onerror = function(error) {
+    error.preventDefault();
+    ok(false, "Worker error " + error.message);
+  }
+  worker.onmessage = function(msg) {
+    ok(true, "MAIN: onmessage " + JSON.stringify(msg.data));
+    switch (msg.data.kind) {
+    case "is":
+      SimpleTest.ok(msg.data.outcome, msg.data.description +
+         "( "+ msg.data.a + " ==? " + msg.data.b + ")" );
+      return;
+    case "isnot":
+      SimpleTest.ok(msg.data.outcome, msg.data.description +
+      "( "+ msg.data.a + " !=? " + msg.data.b + ")" );
+         return;
+    case "ok":
+      SimpleTest.ok(msg.data.condition, msg.data.description);
+      return;
+    case "info":
+      SimpleTest.info(msg.data.description);
+      return;
+    case "finish":
+      SimpleTest.finish();
+      return;
+    default:
+      SimpleTest.ok(false, "test_osfile.xul: wrong message " + JSON.stringify(msg.data));
+      return;
+    }
+  };
+}
diff --git a/toolkit/components/osfile/tests/mochi/worker_test_osfile_comms.js b/toolkit/components/osfile/tests/mochi/worker_test_osfile_comms.js
new file mode 100644
index 000000000..5e8bdd9ca
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/worker_test_osfile_comms.js
@@ -0,0 +1,145 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+importScripts('worker_test_osfile_shared.js');
+
+// The set of samples for communications test. Declare as a global
+// variable to prevent this from being garbage-collected too early.
+var samples;
+
+self.onmessage = function(msg) {
+  info("Initializing");
+  self.onmessage = function on_unexpected_message(msg) {
+    throw new Error("Unexpected message " + JSON.stringify(msg.data));
+  };
+  importScripts("resource://gre/modules/osfile.jsm");
+  info("Initialization complete");
+
+  samples = [
+    { typename: "OS.Shared.Type.char.in_ptr",
+      valuedescr: "String",
+      value: "This is a test",
+      type: OS.Shared.Type.char.in_ptr,
+      check: function check_string(candidate, prefix) {
+        is(candidate, "This is a test", prefix);
+      }},
+    { typename: "OS.Shared.Type.char.in_ptr",
+      valuedescr: "Typed array",
+      value: (function() {
+                let view = new Uint8Array(15);
+                for (let i = 0; i < 15; ++i) {
+                  view[i] = i;
+                }
+                return view;
+              })(),
+      type: OS.Shared.Type.char.in_ptr,
+      check: function check_ArrayBuffer(candidate, prefix) {
+        for (let i = 0; i < 15; ++i) {
+          is(candidate[i], i % 256, prefix + "Checking that the contents of the ArrayBuffer were preserved");
+        }
+      }},
+    { typename: "OS.Shared.Type.char.in_ptr",
+      valuedescr: "Pointer",
+      value: new OS.Shared.Type.char.in_ptr.implementation(1),
+      type: OS.Shared.Type.char.in_ptr,
+      check: function check_ptr(candidate, prefix) {
+        let address = ctypes.cast(candidate, ctypes.uintptr_t).value.toString();
+        is(address, "1", prefix + "Checking that the pointer address was preserved");
+      }},
+    { typename: "OS.Shared.Type.char.in_ptr",
+      valuedescr: "C array",
+      value: (function() {
+                let buf = new (ctypes.ArrayType(ctypes.uint8_t, 15))();
+                for (let i = 0; i < 15; ++i) {
+                  buf[i] = i % 256;
+                }
+                return buf;
+              })(),
+      type: OS.Shared.Type.char.in_ptr,
+      check: function check_array(candidate, prefix) {
+        let cast = ctypes.cast(candidate, ctypes.uint8_t.ptr);
+        for (let i = 0; i < 15; ++i) {
+          is(cast.contents, i % 256, prefix + "Checking that the contents of the C array were preserved, index " + i);
+          cast = cast.increment();
+        }
+      }
+    },
+    { typename: "OS.File.Error",
+      valuedescr: "OS Error",
+      type: OS.File.Error,
+      value: new OS.File.Error("foo", 1),
+      check: function check_error(candidate, prefix) {
+        ok(candidate instanceof OS.File.Error,
+          prefix + "Error is an OS.File.Error");
+        ok(candidate.unixErrno == 1 || candidate.winLastError == 1,
+           prefix + "Error code is correct");
+        try {
+          let string = candidate.toString();
+          info(prefix + ".toString() works " + string);
+        } catch (x) {
+          ok(false, prefix + ".toString() fails " + x);
+        }
+      }
+    }
+  ];
+  samples.forEach(function test(sample) {
+    let type = sample.type;
+    let value = sample.value;
+    let check = sample.check;
+    info("Testing handling of type " + sample.typename + " communicating " + sample.valuedescr);
+
+    // 1. Test serialization
+    let serialized;
+    let exn;
+    try {
+      serialized = type.toMsg(value);
+    } catch (ex) {
+      exn = ex;
+    }
+    is(exn, null, "Can I serialize the following value? " + value +
+      " aka " + JSON.stringify(value));
+    if (exn) {
+      return;
+    }
+
+    if ("data" in serialized) {
+      // Unwrap from `Meta`
+      serialized = serialized.data;
+    }
+
+    // 2. Test deserialization
+    let deserialized;
+    try {
+      deserialized = type.fromMsg(serialized);
+    } catch (ex) {
+      exn = ex;
+    }
+    is(exn, null, "Can I deserialize the following message? " + serialized
+     + " aka " + JSON.stringify(serialized));
+    if (exn) {
+      return;
+    }
+
+    // 3. Local test deserialized value
+    info("Running test on deserialized value " + deserialized +
+      " aka " + JSON.stringify(deserialized));
+    check(deserialized, "Local test: ");
+
+    // 4. Test sending serialized
+    info("Attempting to send message");
+    try {
+      self.postMessage({kind:"value",
+        typename: sample.typename,
+        value: serialized,
+        check: check.toSource()});
+    } catch (ex) {
+      exn = ex;
+    }
+    is(exn, null, "Can I send the following message? " + serialized
+     + " aka " + JSON.stringify(serialized));
+  });
+
+  finish();
+ };
diff --git a/toolkit/components/osfile/tests/mochi/worker_test_osfile_front.js b/toolkit/components/osfile/tests/mochi/worker_test_osfile_front.js
new file mode 100644
index 000000000..29e613510
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/worker_test_osfile_front.js
@@ -0,0 +1,566 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+importScripts('worker_test_osfile_shared.js');
+importScripts("resource://gre/modules/workers/require.js");
+
+var SharedAll = require("resource://gre/modules/osfile/osfile_shared_allthreads.jsm");
+SharedAll.Config.DEBUG = true;
+
+function should_throw(f) {
+  try {
+    f();
+  } catch (x) {
+    return x;
+  }
+  return null;
+}
+
+self.onmessage = function onmessage_start(msg) {
+  self.onmessage = function onmessage_ignored(msg) {
+    log("ignored message " + JSON.stringify(msg.data));
+  };
+  try {
+    test_init();
+    test_open_existing_file();
+    test_open_non_existing_file();
+    test_flush_open_file();
+    test_copy_existing_file();
+    test_position();
+    test_move_file();
+    test_iter_dir();
+    test_info();
+    test_path();
+    test_exists_file();
+    test_remove_file();
+  } catch (x) {
+    log("Catching error: " + x);
+    log("Stack: " + x.stack);
+    log("Source: " + x.toSource());
+    ok(false, x.toString() + "\n" + x.stack);
+  }
+  finish();
+};
+
+function test_init() {
+  info("Starting test_init");
+  importScripts("resource://gre/modules/osfile.jsm");
+}
+
+/**
+ * Test that we can open an existing file.
+ */
+function test_open_existing_file()
+{
+  info("Starting test_open_existing");
+  let file = OS.File.open("chrome/toolkit/components/osfile/tests/mochi/worker_test_osfile_unix.js");
+  file.close();
+}
+
+/**
+ * Test that opening a file that does not exist fails with the right error.
+ */
+function test_open_non_existing_file()
+{
+  info("Starting test_open_non_existing");
+  let exn;
+  try {
+    let file = OS.File.open("/I do not exist");
+  } catch (x) {
+    exn = x;
+    info("test_open_non_existing_file: Exception detail " + exn);
+  }
+  ok(!!exn, "test_open_non_existing_file: Exception was raised ");
+  ok(exn instanceof OS.File.Error, "test_open_non_existing_file: Exception was a OS.File.Error");
+  ok(exn.becauseNoSuchFile, "test_open_non_existing_file: Exception confirms that the file does not exist");
+}
+
+/**
+ * Test that to ensure that |foo.flush()| does not
+ * cause an error, where |foo| is an open file.
+ */
+function test_flush_open_file()
+{
+  info("Starting test_flush_open_file");
+  let tmp = "test_flush.tmp";
+  let file = OS.File.open(tmp, {create: true, write: true});
+  file.flush();
+  file.close();
+  OS.File.remove(tmp);
+}
+
+/**
+ * Utility function for comparing two files (or a prefix of two files).
+ *
+ * This function returns nothing but fails of both files (or prefixes)
+ * are not identical.
+ *
+ * @param {string} test The name of the test (used for logging).
+ * @param {string} sourcePath The name of the first file.
+ * @param {string} destPath The name of the second file.
+ * @param {number=} prefix If specified, only compare the |prefix|
+ * first bytes of |sourcePath| and |destPath|.
+ */
+function compare_files(test, sourcePath, destPath, prefix)
+{
+  info(test + ": Comparing " + sourcePath + " and " + destPath);
+  let source = OS.File.open(sourcePath);
+  let dest = OS.File.open(destPath);
+  info("Files are open");
+  let sourceResult, destResult;
+  try {
+    if (prefix != undefined) {
+      sourceResult = source.read(prefix);
+      destResult = dest.read(prefix);
+    } else {
+      sourceResult = source.read();
+      destResult = dest.read();
+    }
+    is(sourceResult.length, destResult.length, test + ": Both files have the same size");
+    for (let i = 0; i < sourceResult.length; ++i) {
+      if (sourceResult[i] != destResult[i]) {
+        is(sourceResult[i] != destResult[i], test + ": Comparing char " + i);
+        break;
+      }
+    }
+  } finally {
+    source.close();
+    dest.close();
+  }
+  info(test + ": Comparison complete");
+}
+
+/**
+ * Test that copying a file using |copy| works.
+ */
+function test_copy_existing_file()
+{
+  let src_file_name =
+    OS.Path.join("chrome", "toolkit", "components", "osfile", "tests", "mochi",
+                 "worker_test_osfile_front.js");
+  let tmp_file_name = "test_osfile_front.tmp";
+  info("Starting test_copy_existing");
+  OS.File.copy(src_file_name, tmp_file_name);
+
+  info("test_copy_existing: Copy complete");
+  compare_files("test_copy_existing", src_file_name, tmp_file_name);
+
+  // Create a bogus file with arbitrary content, then attempt to overwrite
+  // it with |copy|.
+  let dest = OS.File.open(tmp_file_name, {trunc: true});
+  let buf = new Uint8Array(50);
+  dest.write(buf);
+  dest.close();
+
+  OS.File.copy(src_file_name, tmp_file_name);
+
+  compare_files("test_copy_existing 2", src_file_name, tmp_file_name);
+
+  // Attempt to overwrite with noOverwrite
+  let exn;
+  try {
+    OS.File.copy(src_file_name, tmp_file_name, {noOverwrite: true});
+  } catch(x) {
+    exn = x;
+  }
+  ok(!!exn, "test_copy_existing: noOverwrite prevents overwriting existing files");
+
+  info("test_copy_existing: Cleaning up");
+  OS.File.remove(tmp_file_name);
+}
+
+/**
+ * Test that moving a file works.
+ */
+function test_move_file()
+{
+  info("test_move_file: Starting");
+  // 1. Copy file into a temporary file
+  let src_file_name =
+    OS.Path.join("chrome", "toolkit", "components", "osfile", "tests", "mochi",
+                 "worker_test_osfile_front.js");
+  let tmp_file_name = "test_osfile_front.tmp";
+  let tmp2_file_name = "test_osfile_front.tmp2";
+  OS.File.copy(src_file_name, tmp_file_name);
+
+  info("test_move_file: Copy complete");
+
+  // 2. Move
+  OS.File.move(tmp_file_name, tmp2_file_name);
+
+  info("test_move_file: Move complete");
+
+  // 3. Check that destination exists
+  compare_files("test_move_file", src_file_name, tmp2_file_name);
+
+  // 4. Check that original file does not exist anymore
+  let exn;
+  try {
+    OS.File.open(tmp_file_name);
+  } catch (x) {
+    exn = x;
+  }
+  ok(!!exn, "test_move_file: Original file has been removed");
+
+  info("test_move_file: Cleaning up");
+  OS.File.remove(tmp2_file_name);
+}
+
+function test_iter_dir()
+{
+  info("test_iter_dir: Starting");
+
+  // Create a file, to be sure that it exists
+  let tmp_file_name = "test_osfile_front.tmp";
+  let tmp_file = OS.File.open(tmp_file_name, {write: true, trunc:true});
+  tmp_file.close();
+
+  let parent = OS.File.getCurrentDirectory();
+  info("test_iter_dir: directory " + parent);
+  let iterator = new OS.File.DirectoryIterator(parent);
+  info("test_iter_dir: iterator created");
+  let encountered_tmp_file = false;
+  for (let entry in iterator) {
+    // Checking that |name| can be decoded properly
+    info("test_iter_dir: encountering entry " + entry.name);
+
+    if (entry.name == tmp_file_name) {
+      encountered_tmp_file = true;
+      isnot(entry.isDir, "test_iter_dir: The temporary file is not a directory");
+      isnot(entry.isSymLink, "test_iter_dir: The temporary file is not a link");
+    }
+
+    let file;
+    let success = true;
+    try {
+      file = OS.File.open(entry.path);
+    } catch (x) {
+      if (x.becauseNoSuchFile) {
+        success = false;
+      }
+    }
+    if (file) {
+      file.close();
+    }
+    ok(success, "test_iter_dir: Entry " + entry.path + " exists");
+
+    if (OS.Win) {
+      // We assume that the files are at least as recent as 2009.
+      // Since this test was written in 2011 and some of our packaging
+      // sets dates arbitrarily to 2010, this should be safe.
+      let year = new Date().getFullYear();
+      let creation = entry.winCreationDate;
+      ok(creation, "test_iter_dir: Windows creation date exists: " + creation);
+      ok(creation.getFullYear() >= 2009 && creation.getFullYear() <= year, "test_iter_dir: consistent creation date");
+
+      let lastWrite = entry.winLastWriteDate;
+      ok(lastWrite, "test_iter_dir: Windows lastWrite date exists: " + lastWrite);
+      ok(lastWrite.getFullYear() >= 2009 && lastWrite.getFullYear() <= year, "test_iter_dir: consistent lastWrite date");
+
+      let lastAccess = entry.winLastAccessDate;
+      ok(lastAccess, "test_iter_dir: Windows lastAccess date exists: " + lastAccess);
+      ok(lastAccess.getFullYear() >= 2009 && lastAccess.getFullYear() <= year, "test_iter_dir: consistent lastAccess date");
+    }
+
+  }
+  ok(encountered_tmp_file, "test_iter_dir: We have found the temporary file");
+
+  info("test_iter_dir: Cleaning up");
+  iterator.close();
+
+  // Testing nextBatch()
+  iterator = new OS.File.DirectoryIterator(parent);
+  let allentries = [];
+  for (let x in iterator) {
+    allentries.push(x);
+  }
+  iterator.close();
+
+  ok(allentries.length >= 14, "test_iter_dir: Meta-check: the test directory should contain at least 14 items");
+
+  iterator = new OS.File.DirectoryIterator(parent);
+  let firstten = iterator.nextBatch(10);
+  is(firstten.length, 10, "test_iter_dir: nextBatch(10) returns 10 items");
+  for (let i = 0; i < firstten.length; ++i) {
+    is(allentries[i].path, firstten[i].path, "test_iter_dir: Checking that batch returns the correct entries");
+  }
+  let nextthree = iterator.nextBatch(3);
+  is(nextthree.length, 3, "test_iter_dir: nextBatch(3) returns 3 items");
+  for (let i = 0; i < nextthree.length; ++i) {
+    is(allentries[i + firstten.length].path, nextthree[i].path, "test_iter_dir: Checking that batch 2 returns the correct entries");
+  }
+  let everythingelse = iterator.nextBatch();
+  ok(everythingelse.length >= 1, "test_iter_dir: nextBatch() returns at least one item");
+  for (let i = 0; i < everythingelse.length; ++i) {
+    is(allentries[i + firstten.length + nextthree.length].path, everythingelse[i].path, "test_iter_dir: Checking that batch 3 returns the correct entries");
+  }
+  is(iterator.nextBatch().length, 0, "test_iter_dir: Once there is nothing left, nextBatch returns an empty array");
+  iterator.close();
+
+  iterator = new OS.File.DirectoryIterator(parent);
+  iterator.close();
+  is(iterator.nextBatch().length, 0, "test_iter_dir: nextBatch on closed iterator returns an empty array");
+
+  iterator = new OS.File.DirectoryIterator(parent);
+  let allentries2 = iterator.nextBatch();
+  is(allentries.length, allentries2.length, "test_iter_dir: Checking that getBatch(null) returns the right number of entries");
+  for (let i = 0; i < allentries.length; ++i) {
+    is(allentries[i].path, allentries2[i].path, "test_iter_dir: Checking that getBatch(null) returns everything in the right order");
+  }
+  iterator.close();
+
+  // Test forEach
+  iterator = new OS.File.DirectoryIterator(parent);
+  let index = 0;
+  iterator.forEach(
+    function cb(entry, aIndex, aIterator) {
+      is(index, aIndex, "test_iter_dir: Checking that forEach index is correct");
+      ok(iterator == aIterator, "test_iter_dir: Checking that right iterator is passed");
+      if (index < 10) {
+        is(allentries[index].path, entry.path, "test_iter_dir: Checking that forEach entry is correct");
+      } else if (index == 10) {
+        iterator.close();
+      } else {
+        ok(false, "test_iter_dir: Checking that forEach can be stopped early");
+      }
+      ++index;
+  });
+  iterator.close();
+
+  //test for prototype |OS.File.DirectoryIterator.unixAsFile|
+  if ("unixAsFile" in OS.File.DirectoryIterator.prototype) {
+    info("testing property unixAsFile");
+    let path = OS.Path.join("chrome", "toolkit", "components", "osfile", "tests", "mochi");
+    iterator = new OS.File.DirectoryIterator(path);
+
+    let dir_file = iterator.unixAsFile();// return |File|
+    let stat0 = dir_file.stat();
+    let stat1 = OS.File.stat(path);
+
+    let unix_info_to_string = function unix_info_to_string(info) {
+      return "| " + info.unixMode + " | " + info.unixOwner + " | " + info.unixGroup + " | " + info.creationDate + " | " + info.lastModificationDate + " | " + info.lastAccessDate + " | " + info.size + " |";
+    };
+
+    let s0_string = unix_info_to_string(stat0);
+    let s1_string = unix_info_to_string(stat1);
+
+    ok(stat0.isDir, "unixAsFile returned a directory");
+    is(s0_string, s1_string, "unixAsFile returned the correct file");
+    dir_file.close();
+    iterator.close();
+  }
+  info("test_iter_dir: Complete");
+}
+
+function test_position() {
+  info("test_position: Starting");
+
+  ok("POS_START" in OS.File, "test_position: POS_START exists");
+  ok("POS_CURRENT" in OS.File, "test_position: POS_CURRENT exists");
+  ok("POS_END" in OS.File, "test_position: POS_END exists");
+
+  let ARBITRARY_POSITION = 321;
+  let src_file_name =
+    OS.Path.join("chrome", "toolkit", "components", "osfile", "tests", "mochi",
+                 "worker_test_osfile_front.js");
+
+  let file = OS.File.open(src_file_name);
+  is(file.getPosition(), 0, "test_position: Initial position is 0");
+
+  let size = 0 + file.stat().size; // Hack: We can remove this 0 + once 776259 has landed
+
+  file.setPosition(ARBITRARY_POSITION, OS.File.POS_START);
+  is(file.getPosition(), ARBITRARY_POSITION, "test_position: Setting position from start");
+
+  file.setPosition(0, OS.File.POS_START);
+  is(file.getPosition(), 0, "test_position: Setting position from start back to 0");
+
+  file.setPosition(ARBITRARY_POSITION);
+  is(file.getPosition(), ARBITRARY_POSITION, "test_position: Setting position without argument");
+
+  file.setPosition(-ARBITRARY_POSITION, OS.File.POS_END);
+  is(file.getPosition(), size - ARBITRARY_POSITION, "test_position: Setting position from end");
+
+  file.setPosition(ARBITRARY_POSITION, OS.File.POS_CURRENT);
+  is(file.getPosition(), size, "test_position: Setting position from current");
+
+  file.close();
+  info("test_position: Complete");
+}
+
+function test_info() {
+  info("test_info: Starting");
+
+  let filename = "test_info.tmp";
+  let size = 261;// An arbitrary file length
+  let start = new Date();
+
+ // Cleanup any leftover from previous tests
+  try {
+    OS.File.remove(filename);
+    info("test_info: Cleaned up previous garbage");
+  } catch (x) {
+    if (!x.becauseNoSuchFile) {
+      throw x;
+    }
+    info("test_info: No previous garbage");
+  }
+
+  let file = OS.File.open(filename, {trunc: true});
+  let buf = new ArrayBuffer(size);
+  file._write(buf, size);
+  file.close();
+
+  // Test OS.File.stat on new file
+  let stat = OS.File.stat(filename);
+  ok(!!stat, "test_info: info acquired");
+  ok(!stat.isDir, "test_info: file is not a directory");
+  is(stat.isSymLink, false, "test_info: file is not a link");
+  is(stat.size.toString(), size, "test_info: correct size");
+
+  let stop = new Date();
+
+  // We round down/up by 1s as file system precision is lower than
+  // Date precision (no clear specifications about that, but it seems
+  // that this can be a little over 1 second under ext3 and 2 seconds
+  // under FAT).
+  let SLOPPY_FILE_SYSTEM_ADJUSTMENT = 3000;
+  let startMs = start.getTime() - SLOPPY_FILE_SYSTEM_ADJUSTMENT;
+  let stopMs  = stop.getTime() + SLOPPY_FILE_SYSTEM_ADJUSTMENT;
+  info("Testing stat with bounds [ " + startMs + ", " + stopMs +" ]");
+
+  (function() {
+    let birth;
+    if ("winBirthDate" in stat) {
+      birth = stat.winBirthDate;
+    } else if ("macBirthDate" in stat) {
+      birth = stat.macBirthDate;
+    } else {
+      ok(true, "Skipping birthdate test");
+      return;
+    }
+    ok(birth.getTime() <= stopMs,
+    "test_info: platformBirthDate is consistent");
+    // Note: Previous versions of this test checked whether the file
+    // has been created after the start of the test. Unfortunately,
+    // this sometimes failed under Windows, in specific circumstances:
+    // if the file has been removed at the start of the test and
+    // recreated immediately, the Windows file system detects this and
+    // decides that the file was actually truncated rather than
+    // recreated, hence that it should keep its previous creation
+    // date.  Debugging hilarity ensues.
+  });
+
+  let change = stat.lastModificationDate;
+  info("Testing lastModificationDate: " + change);
+  ok(change.getTime() >= startMs && change.getTime() <= stopMs,
+     "test_info: lastModificationDate is consistent");
+
+  // Test OS.File.prototype.stat on new file
+  file = OS.File.open(filename);
+  try {
+    stat = file.stat();
+  } finally {
+    file.close();
+  }
+
+  ok(!!stat, "test_info: info acquired 2");
+  ok(!stat.isDir, "test_info: file is not a directory 2");
+  ok(!stat.isSymLink, "test_info: file is not a link 2");
+  is(stat.size.toString(), size, "test_info: correct size 2");
+
+  stop = new Date();
+
+  // Round up/down as above
+  startMs = start.getTime() - SLOPPY_FILE_SYSTEM_ADJUSTMENT;
+  stopMs  = stop.getTime() + SLOPPY_FILE_SYSTEM_ADJUSTMENT;
+  info("Testing stat 2 with bounds [ " + startMs + ", " + stopMs +" ]");
+
+  let access = stat.lastAccessDate;
+  info("Testing lastAccessDate: " + access);
+  ok(access.getTime() >= startMs && access.getTime() <= stopMs,
+     "test_info: lastAccessDate is consistent");
+
+  change = stat.lastModificationDate;
+  info("Testing lastModificationDate 2: " + change);
+  ok(change.getTime() >= startMs && change.getTime() <= stopMs,
+     "test_info: lastModificationDate 2 is consistent");
+
+  // Test OS.File.stat on directory
+  stat = OS.File.stat(OS.File.getCurrentDirectory());
+  ok(!!stat, "test_info: info on directory acquired");
+  ok(stat.isDir, "test_info: directory is a directory");
+
+  info("test_info: Complete");
+}
+
+// Note that most of the features of path are tested in
+// worker_test_osfile_{unix, win}.js
+function test_path()
+{
+  info("test_path: starting");
+  let abcd = OS.Path.join("a", "b", "c", "d");
+  is(OS.Path.basename(abcd), "d", "basename of a/b/c/d");
+
+  let abc = OS.Path.join("a", "b", "c");
+  is(OS.Path.dirname(abcd), abc, "dirname of a/b/c/d");
+
+  let abdotsc = OS.Path.join("a", "b", "..", "c");
+  is(OS.Path.normalize(abdotsc), OS.Path.join("a", "c"), "normalize a/b/../c");
+
+  let adotsdotsdots = OS.Path.join("a", "..", "..", "..");
+  is(OS.Path.normalize(adotsdotsdots), OS.Path.join("..", ".."), "normalize a/../../..");
+
+  info("test_path: Complete");
+}
+
+/**
+ * Test the file |exists| method.
+ */
+function test_exists_file()
+{
+  let file_name = OS.Path.join("chrome", "toolkit", "components" ,"osfile",
+                               "tests", "mochi", "test_osfile_front.xul");
+  info("test_exists_file: starting");
+  ok(OS.File.exists(file_name), "test_exists_file: file exists (OS.File.exists)");
+  ok(!OS.File.exists(file_name + ".tmp"), "test_exists_file: file does not exists (OS.File.exists)");
+
+  let dir_name = OS.Path.join("chrome", "toolkit", "components" ,"osfile",
+                               "tests", "mochi");
+  ok(OS.File.exists(dir_name), "test_exists_file: directory exists");
+  ok(!OS.File.exists(dir_name) + ".tmp", "test_exists_file: directory does not exist");
+
+  info("test_exists_file: complete");
+}
+
+/**
+ * Test the file |remove| method.
+ */
+function test_remove_file()
+{
+  let absent_file_name = "test_osfile_front_absent.tmp";
+
+  // Check that removing absent files is handled correctly
+  let exn = should_throw(function() {
+    OS.File.remove(absent_file_name, {ignoreAbsent: false});
+  });
+  ok(!!exn, "test_remove_file: throws if there is no such file");
+
+  exn = should_throw(function() {
+    OS.File.remove(absent_file_name, {ignoreAbsent: true});
+    OS.File.remove(absent_file_name);
+  });
+  ok(!exn, "test_remove_file: ignoreAbsent works");
+
+  if (OS.Win) {
+    let file_name = "test_osfile_front_file_to_remove.tmp";
+    let file = OS.File.open(file_name, {write: true});
+    file.close();
+    ok(OS.File.exists(file_name), "test_remove_file: test file exists");
+    OS.Win.File.SetFileAttributes(file_name,
+                                  OS.Constants.Win.FILE_ATTRIBUTE_READONLY);
+    OS.File.remove(file_name);
+    ok(!OS.File.exists(file_name),
+       "test_remove_file: test file has been removed");
+  }
+}
diff --git a/toolkit/components/osfile/tests/mochi/worker_test_osfile_shared.js b/toolkit/components/osfile/tests/mochi/worker_test_osfile_shared.js
new file mode 100644
index 000000000..da82d4b0a
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/worker_test_osfile_shared.js
@@ -0,0 +1,32 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function log(text) {
+  dump("WORKER " + text + "\n");
+}
+
+function send(message) {
+  self.postMessage(message);
+}
+
+function finish() {
+  send({kind: "finish"});
+}
+
+function ok(condition, description) {
+  send({kind: "ok", condition: !!condition, description: "" + description});
+}
+
+function is(a, b, description) {
+  let outcome = a == b; // Need to decide outcome here, as not everything can be serialized
+  send({kind: "is", outcome: outcome, description: "" + description, a: "" + a, b: "" + b});
+}
+
+function isnot(a, b, description) {
+  let outcome = a != b; // Need to decide outcome here, as not everything can be serialized
+  send({kind: "isnot", outcome: outcome, description: "" + description, a: "" + a, b: "" + b});
+}
+
+function info(description) {
+  send({kind: "info", description: "" + description});
+}
diff --git a/toolkit/components/osfile/tests/mochi/worker_test_osfile_unix.js b/toolkit/components/osfile/tests/mochi/worker_test_osfile_unix.js
new file mode 100644
index 000000000..9fe2d0b4e
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/worker_test_osfile_unix.js
@@ -0,0 +1,201 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+importScripts('worker_test_osfile_shared.js');
+
+self.onmessage = function(msg) {
+  log("received message "+JSON.stringify(msg.data));
+  self.onmessage = function(msg) {
+    log("ignored message "+JSON.stringify(msg.data));
+  };
+  test_init();
+  test_getcwd();
+  test_open_close();
+  test_create_file();
+  test_access();
+  test_read_write();
+  test_passing_undefined();
+  finish();
+};
+
+function test_init() {
+  info("Starting test_init");
+  importScripts("resource://gre/modules/osfile.jsm");
+}
+
+function test_open_close() {
+  info("Starting test_open_close");
+  is(typeof OS.Unix.File.open, "function", "OS.Unix.File.open is a function");
+  let file = OS.Unix.File.open("chrome/toolkit/components/osfile/tests/mochi/worker_test_osfile_unix.js", OS.Constants.libc.O_RDONLY, 0);
+  isnot(file, -1, "test_open_close: opening succeeded");
+  info("Close: "+OS.Unix.File.close.toSource());
+  let result = OS.Unix.File.close(file);
+  is(result, 0, "test_open_close: close succeeded");
+
+  file = OS.Unix.File.open("/i do not exist", OS.Constants.libc.O_RDONLY, 0);
+  is(file, -1, "test_open_close: opening of non-existing file failed");
+  is(ctypes.errno, OS.Constants.libc.ENOENT, "test_open_close: error is ENOENT");
+}
+
+function test_create_file()
+{
+  info("Starting test_create_file");
+  let file = OS.Unix.File.open("test.tmp", OS.Constants.libc.O_RDWR
+                               | OS.Constants.libc.O_CREAT
+                               | OS.Constants.libc.O_TRUNC,
+                               OS.Constants.libc.S_IRWXU);
+  isnot(file, -1, "test_create_file: file created");
+  OS.Unix.File.close(file);
+}
+
+function test_access()
+{
+  info("Starting test_access");
+  let file = OS.Unix.File.open("test1.tmp", OS.Constants.libc.O_RDWR
+                               | OS.Constants.libc.O_CREAT
+                               | OS.Constants.libc.O_TRUNC,
+                               OS.Constants.libc.S_IRWXU);
+  let result = OS.Unix.File.access("test1.tmp", OS.Constants.libc.R_OK | OS.Constants.libc.W_OK | OS.Constants.libc.X_OK | OS.Constants.libc.F_OK);
+  is(result, 0, "first call to access() succeeded");
+  OS.Unix.File.close(file);
+
+  file = OS.Unix.File.open("test1.tmp", OS.Constants.libc.O_WRONLY
+                               | OS.Constants.libc.O_CREAT
+                               | OS.Constants.libc.O_TRUNC,
+                               OS.Constants.libc.S_IWUSR);
+
+  info("test_access: preparing second call to access()");
+  result = OS.Unix.File.access("test2.tmp", OS.Constants.libc.R_OK
+                        | OS.Constants.libc.W_OK
+                        | OS.Constants.libc.X_OK
+                        | OS.Constants.libc.F_OK);
+  is(result, -1, "test_access: second call to access() failed as expected");
+  is(ctypes.errno, OS.Constants.libc.ENOENT, "This is the correct error");
+  OS.Unix.File.close(file);
+}
+
+function test_getcwd()
+{
+  let array = new (ctypes.ArrayType(ctypes.char, 32768))();
+  let path = OS.Unix.File.getcwd(array, array.length);
+  if (ctypes.char.ptr(path).isNull()) {
+    ok(false, "test_get_cwd: getcwd returned null, errno: " + ctypes.errno);
+  }
+  let path2;
+  if (OS.Unix.File.get_current_dir_name) {
+    path2 = OS.Unix.File.get_current_dir_name();
+  } else {
+    path2 = OS.Unix.File.getwd_auto(null);
+  }
+  if (ctypes.char.ptr(path2).isNull()) {
+    ok(false, "test_get_cwd: getwd_auto/get_current_dir_name returned null, errno: " + ctypes.errno);
+  }
+  is(path.readString(), path2.readString(), "test_get_cwd: getcwd and getwd return the same path");
+}
+
+function test_read_write()
+{
+  let output_name = "osfile_copy.tmp";
+  // Copy file
+  let input = OS.Unix.File.open(
+    "chrome/toolkit/components/osfile/tests/mochi/worker_test_osfile_unix.js",
+    OS.Constants.libc.O_RDONLY, 0);
+  isnot(input, -1, "test_read_write: input file opened");
+  let output = OS.Unix.File.open("osfile_copy.tmp", OS.Constants.libc.O_RDWR
+    | OS.Constants.libc.O_CREAT
+    | OS.Constants.libc.O_TRUNC,
+    OS.Constants.libc.S_IRWXU);
+  isnot(output, -1, "test_read_write: output file opened");
+
+  let array = new (ctypes.ArrayType(ctypes.char, 4096))();
+  let bytes = -1;
+  let total = 0;
+  while (true) {
+    bytes = OS.Unix.File.read(input, array, 4096);
+    ok(bytes != undefined, "test_read_write: bytes is defined");
+    isnot(bytes, -1, "test_read_write: no read error");
+    let write_from = 0;
+    if (bytes == 0) {
+      break;
+    }
+    while (bytes > 0) {
+      let ptr = array.addressOfElement(write_from);
+      // Note: |write| launches an exception in case of error
+      let written = OS.Unix.File.write(output, array, bytes);
+      isnot(written, -1, "test_read_write: no write error");
+      write_from += written;
+      bytes -= written;
+    }
+    total += write_from;
+  }
+  info("test_read_write: copy complete " + total);
+
+  // Compare files
+  let result;
+  info("SEEK_SET: " + OS.Constants.libc.SEEK_SET);
+  info("Input: " + input + "(" + input.toSource() + ")");
+  info("Output: " + output + "(" + output.toSource() + ")");
+  result = OS.Unix.File.lseek(input, 0, OS.Constants.libc.SEEK_SET);
+  info("Result of lseek: " + result);
+  isnot(result, -1, "test_read_write: input seek succeeded " + ctypes.errno);
+  result = OS.Unix.File.lseek(output, 0, OS.Constants.libc.SEEK_SET);
+  isnot(result, -1, "test_read_write: output seek succeeded " + ctypes.errno);
+
+  let array2 = new (ctypes.ArrayType(ctypes.char, 4096))();
+  let bytes2 = -1;
+  let pos = 0;
+  while (true) {
+    bytes = OS.Unix.File.read(input, array, 4096);
+    isnot(bytes, -1, "test_read_write: input read succeeded");
+    bytes2 = OS.Unix.File.read(output, array2, 4096);
+    isnot(bytes, -1, "test_read_write: output read succeeded");
+    is(bytes > 0, bytes2 > 0, "Both files contain data or neither does "+bytes+", "+bytes2);
+    if (bytes == 0) {
+      break;
+    }
+    if (bytes != bytes2) {
+      // This would be surprising, but theoretically possible with a
+      // remote file system, I believe.
+      bytes = Math.min(bytes, bytes2);
+      pos += bytes;
+      result = OS.Unix.File.lseek(input, pos, OS.Constants.libc.SEEK_SET);
+      isnot(result, -1, "test_read_write: input seek succeeded");
+      result = OS.Unix.File.lseek(output, pos, OS.Constants.libc.SEEK_SET);
+      isnot(result, -1, "test_read_write: output seek succeeded");
+    } else {
+      pos += bytes;
+    }
+    for (let i = 0; i < bytes; ++i) {
+      if (array[i] != array2[i]) {
+        ok(false, "Files do not match at position " + i
+           + " ("+array[i] + "/"+array2[i] + ")");
+      }
+    }
+  }
+  info("test_read_write test complete");
+  result = OS.Unix.File.close(input);
+  isnot(result, -1, "test_read_write: input close succeeded");
+  result = OS.Unix.File.close(output);
+  isnot(result, -1, "test_read_write: output close succeeded");
+  result = OS.Unix.File.unlink(output_name);
+  isnot(result, -1, "test_read_write: input remove succeeded");
+  info("test_read_write cleanup complete");
+}
+
+function test_passing_undefined()
+{
+  info("Testing that an exception gets thrown when an FFI function is passed undefined");
+  let exceptionRaised = false;
+
+  try {
+    let file = OS.Unix.File.open(undefined, OS.Constants.libc.O_RDWR
+                                            | OS.Constants.libc.O_CREAT
+                                            | OS.Constants.libc.O_TRUNC,
+                                            OS.Constants.libc.S_IRWXU);
+  } catch(e if e instanceof TypeError && e.message.indexOf("open") > -1) {
+    exceptionRaised = true;
+  }
+
+  ok(exceptionRaised, "test_passing_undefined: exception gets thrown")
+}
+
diff --git a/toolkit/components/osfile/tests/mochi/worker_test_osfile_win.js b/toolkit/components/osfile/tests/mochi/worker_test_osfile_win.js
new file mode 100644
index 000000000..f41fdecfe
--- /dev/null
+++ b/toolkit/components/osfile/tests/mochi/worker_test_osfile_win.js
@@ -0,0 +1,211 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+importScripts('worker_test_osfile_shared.js');
+
+self.onmessage = function(msg) {
+  self.onmessage = function(msg) {
+    log("ignored message "+JSON.stringify(msg.data));
+  };
+
+  test_init();
+  test_GetCurrentDirectory();
+  test_OpenClose();
+  test_CreateFile();
+  test_ReadWrite();
+  test_passing_undefined();
+  finish();
+};
+
+function test_init() {
+  info("Starting test_init");
+  importScripts("resource://gre/modules/osfile.jsm");
+}
+
+function test_OpenClose() {
+  info("Starting test_OpenClose");
+  is(typeof OS.Win.File.CreateFile, "function", "OS.Win.File.CreateFile is a function");
+  is(OS.Win.File.CloseHandle(OS.Constants.Win.INVALID_HANDLE_VALUE), true, "CloseHandle returns true given the invalid handle");
+  is(OS.Win.File.FindClose(OS.Constants.Win.INVALID_HANDLE_VALUE), true, "FindClose returns true given the invalid handle");
+  isnot(OS.Constants.Win.GENERIC_READ, undefined, "GENERIC_READ exists");
+  isnot(OS.Constants.Win.FILE_SHARE_READ, undefined, "FILE_SHARE_READ exists");
+  isnot(OS.Constants.Win.FILE_ATTRIBUTE_NORMAL, undefined, "FILE_ATTRIBUTE_NORMAL exists");
+  let file = OS.Win.File.CreateFile(
+    "chrome\\toolkit\\components\\osfile\\tests\\mochi\\worker_test_osfile_win.js",
+    OS.Constants.Win.GENERIC_READ,
+    0,
+    null,
+    OS.Constants.Win.OPEN_EXISTING,
+    0,
+    null);
+  info("test_OpenClose: Passed open");
+  isnot(file, OS.Constants.Win.INVALID_HANDLE_VALUE, "test_OpenClose: file opened");
+  let result = OS.Win.File.CloseHandle(file);
+  isnot(result, 0, "test_OpenClose: close succeeded");
+
+  file = OS.Win.File.CreateFile(
+    "\\I do not exist",
+    OS.Constants.Win.GENERIC_READ,
+    OS.Constants.Win.FILE_SHARE_READ,
+    null,
+    OS.Constants.Win.OPEN_EXISTING,
+    OS.Constants.Win.FILE_ATTRIBUTE_NORMAL,
+    null);
+  is(file, OS.Constants.Win.INVALID_HANDLE_VALUE, "test_OpenClose: cannot open non-existing file");
+  is(ctypes.winLastError, OS.Constants.Win.ERROR_FILE_NOT_FOUND, "test_OpenClose: error is ERROR_FILE_NOT_FOUND");
+}
+
+function test_CreateFile()
+{
+  info("Starting test_CreateFile");
+  let file = OS.Win.File.CreateFile(
+    "test.tmp",
+    OS.Constants.Win.GENERIC_READ | OS.Constants.Win.GENERIC_WRITE,
+    OS.Constants.Win.FILE_SHARE_READ | OS.Constants.FILE_SHARE_WRITE,
+    null,
+    OS.Constants.Win.CREATE_ALWAYS,
+    OS.Constants.Win.FILE_ATTRIBUTE_NORMAL,
+    null);
+  isnot(file, OS.Constants.Win.INVALID_HANDLE_VALUE, "test_CreateFile: opening succeeded");
+  let result = OS.Win.File.CloseHandle(file);
+  isnot(result, 0, "test_CreateFile: close succeeded");
+}
+
+function test_GetCurrentDirectory()
+{
+  let array = new (ctypes.ArrayType(ctypes.char16_t, 4096))();
+  let result = OS.Win.File.GetCurrentDirectory(4096, array);
+  ok(result < array.length, "test_GetCurrentDirectory: length sufficient");
+  ok(result > 0, "test_GetCurrentDirectory: length != 0");
+}
+
+function test_ReadWrite()
+{
+  info("Starting test_ReadWrite");
+  let output_name = "osfile_copy.tmp";
+  // Copy file
+  let input = OS.Win.File.CreateFile(
+    "chrome\\toolkit\\components\\osfile\\tests\\mochi\\worker_test_osfile_win.js",
+     OS.Constants.Win.GENERIC_READ,
+     0,
+     null,
+     OS.Constants.Win.OPEN_EXISTING,
+     0,
+     null);
+  isnot(input, OS.Constants.Win.INVALID_HANDLE_VALUE, "test_ReadWrite: input file opened");
+  let output = OS.Win.File.CreateFile(
+     "osfile_copy.tmp",
+     OS.Constants.Win.GENERIC_READ | OS.Constants.Win.GENERIC_WRITE,
+     0,
+     null,
+     OS.Constants.Win.CREATE_ALWAYS,
+     OS.Constants.Win.FILE_ATTRIBUTE_NORMAL,
+     null);
+  isnot(output, OS.Constants.Win.INVALID_HANDLE_VALUE, "test_ReadWrite: output file opened");
+  let array = new (ctypes.ArrayType(ctypes.char, 4096))();
+  let bytes_read = new ctypes.uint32_t(0);
+  let bytes_read_ptr = bytes_read.address();
+  log("We have a pointer for bytes read: "+bytes_read_ptr);
+  let bytes_written = new ctypes.uint32_t(0);
+  let bytes_written_ptr = bytes_written.address();
+  log("We have a pointer for bytes written: "+bytes_written_ptr);
+  log("test_ReadWrite: buffer and pointers ready");
+  let result;
+  while (true) {
+    log("test_ReadWrite: reading");
+    result = OS.Win.File.ReadFile(input, array, 4096, bytes_read_ptr, null);
+    isnot (result, 0, "test_ReadWrite: read success");
+    let write_from = 0;
+    let bytes_left = bytes_read;
+    log("test_ReadWrite: read chunk complete " + bytes_left.value);
+    if (bytes_left.value == 0) {
+      break;
+    }
+    while (bytes_left.value > 0) {
+      log("test_ReadWrite: writing "+bytes_left.value);
+      let ptr = array.addressOfElement(write_from);
+      // Note: |WriteFile| launches an exception in case of error
+      result = OS.Win.File.WriteFile(output, array, bytes_left, bytes_written_ptr, null);
+      isnot (result, 0, "test_ReadWrite: write success");
+      write_from += bytes_written;
+      bytes_left -= bytes_written;
+    }
+  }
+  info("test_ReadWrite: copy complete");
+
+  // Compare files
+  result = OS.Win.File.SetFilePointer(input, 0, null, OS.Constants.Win.FILE_BEGIN);
+  isnot (result, OS.Constants.Win.INVALID_SET_FILE_POINTER, "test_ReadWrite: input reset");
+
+  result = OS.Win.File.SetFilePointer(output, 0, null, OS.Constants.Win.FILE_BEGIN);
+  isnot (result, OS.Constants.Win.INVALID_SET_FILE_POINTER, "test_ReadWrite: output reset");
+
+  let array2 = new (ctypes.ArrayType(ctypes.char, 4096))();
+  let bytes_read2 = new ctypes.uint32_t(0);
+  let bytes_read2_ptr = bytes_read2.address();
+  let pos = 0;
+  while (true) {
+    result = OS.Win.File.ReadFile(input, array, 4096, bytes_read_ptr, null);
+    isnot(result, 0, "test_ReadWrite: input read succeeded");
+
+    result = OS.Win.File.ReadFile(output, array2, 4096, bytes_read2_ptr, null);
+    isnot(result, 0, "test_ReadWrite: output read succeeded");
+
+    is(bytes_read.value > 0, bytes_read2.value > 0,
+       "Both files contain data or neither does " + bytes_read.value + ", " + bytes_read2.value);
+    if (bytes_read.value == 0) {
+      break;
+    }
+    let bytes;
+    if (bytes_read.value != bytes_read2.value) {
+      // This would be surprising, but theoretically possible with a
+      // remote file system, I believe.
+      bytes = Math.min(bytes_read.value, bytes_read2.value);
+      pos += bytes;
+      result = OS.Win.File.SetFilePointer(input,  pos, null, OS.Constants.Win.FILE_BEGIN);
+      isnot(result, 0, "test_ReadWrite: input seek succeeded");
+
+      result = OS.Win.File.SetFilePointer(output, pos, null, OS.Constants.Win.FILE_BEGIN);
+      isnot(result, 0, "test_ReadWrite: output seek succeeded");
+
+    } else {
+      bytes = bytes_read.value;
+      pos += bytes;
+    }
+    for (let i = 0; i < bytes; ++i) {
+      if (array[i] != array2[i]) {
+        ok(false, "Files do not match at position " + i
+           + " ("+array[i] + "/"+array2[i] + ")");
+      }
+    }
+  }
+  info("test_ReadWrite test complete");
+  result = OS.Win.File.CloseHandle(input);
+  isnot(result, 0, "test_ReadWrite: inpout close succeeded");
+  result = OS.Win.File.CloseHandle(output);
+  isnot(result, 0, "test_ReadWrite: outpout close succeeded");
+  result = OS.Win.File.DeleteFile(output_name);
+  isnot(result, 0, "test_ReadWrite: output remove succeeded");
+  info("test_ReadWrite cleanup complete");
+}
+
+function test_passing_undefined()
+{
+  info("Testing that an exception gets thrown when an FFI function is passed undefined");
+  let exceptionRaised = false;
+
+  try {
+    let file = OS.Win.File.CreateFile(
+      undefined,
+      OS.Constants.Win.GENERIC_READ,
+      0,
+      null,
+      OS.Constants.Win.OPEN_EXISTING,
+      0,
+      null);
+  } catch(e if e instanceof TypeError && e.message.indexOf("CreateFile") > -1) {
+    exceptionRaised = true;
+  }
+
+  ok(exceptionRaised, "test_passing_undefined: exception gets thrown")
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/.eslintrc.js b/toolkit/components/osfile/tests/xpcshell/.eslintrc.js
new file mode 100644
index 000000000..d35787cd2
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/.eslintrc.js
@@ -0,0 +1,7 @@
+"use strict";
+
+module.exports = {
+  "extends": [
+    "../../../../../testing/xpcshell/xpcshell.eslintrc.js"
+  ]
+};
diff --git a/toolkit/components/osfile/tests/xpcshell/head.js b/toolkit/components/osfile/tests/xpcshell/head.js
new file mode 100644
index 000000000..eef29962a
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/head.js
@@ -0,0 +1,99 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+var {utils: Cu, interfaces: Ci} = Components;
+
+var {XPCOMUtils} = Cu.import("resource://gre/modules/XPCOMUtils.jsm", {});
+
+// Bug 1014484 can only be reproduced by loading OS.File first from the
+// CommonJS loader, so we do not want OS.File to be loaded eagerly for
+// all the tests in this directory.
+XPCOMUtils.defineLazyModuleGetter(this, "OS",
+  "resource://gre/modules/osfile.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
+  "resource://gre/modules/FileUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
+  "resource://gre/modules/NetUtil.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "Services",
+  "resource://gre/modules/Services.jsm");
+
+var {Promise} = Cu.import("resource://gre/modules/Promise.jsm", {});
+var {Task} = Cu.import("resource://gre/modules/Task.jsm", {});
+
+Services.prefs.setBoolPref("toolkit.osfile.log", true);
+
+/**
+ * As add_task, but execute the test both with native operations and
+ * without.
+ */
+function add_test_pair(generator) {
+  add_task(function*() {
+    do_print("Executing test " + generator.name + " with native operations");
+    Services.prefs.setBoolPref("toolkit.osfile.native", true);
+    return Task.spawn(generator);
+  });
+  add_task(function*() {
+    do_print("Executing test " + generator.name + " without native operations");
+    Services.prefs.setBoolPref("toolkit.osfile.native", false);
+    return Task.spawn(generator);
+  });
+}
+
+/**
+ * Fetch asynchronously the contents of a file using xpcom.
+ *
+ * Used for comparing xpcom-based results to os.file-based results.
+ *
+ * @param {string} path The _absolute_ path to the file.
+ * @return {promise}
+ * @resolves {string} The contents of the file.
+ */
+function reference_fetch_file(path, test) {
+  do_print("Fetching file " + path);
+  let deferred = Promise.defer();
+  let file = new FileUtils.File(path);
+  NetUtil.asyncFetch({
+    uri: NetUtil.newURI(file),
+    loadUsingSystemPrincipal: true
+  }, function(stream, status) {
+      if (!Components.isSuccessCode(status)) {
+        deferred.reject(status);
+        return;
+      }
+      let result, reject;
+      try {
+        result = NetUtil.readInputStreamToString(stream, stream.available());
+      } catch (x) {
+        reject = x;
+      }
+      stream.close();
+      if (reject) {
+        deferred.reject(reject);
+      } else {
+        deferred.resolve(result);
+      }
+    });
+
+  return deferred.promise;
+};
+
+/**
+ * Compare asynchronously the contents two files using xpcom.
+ *
+ * Used for comparing xpcom-based results to os.file-based results.
+ *
+ * @param {string} a The _absolute_ path to the first file.
+ * @param {string} b The _absolute_ path to the second file.
+ *
+ * @resolves {null}
+ */
+function reference_compare_files(a, b, test) {
+  return Task.spawn(function*() {
+    do_print("Comparing files " + a + " and " + b);
+    let a_contents = yield reference_fetch_file(a, test);
+    let b_contents = yield reference_fetch_file(b, test);
+    do_check_eq(a_contents, b_contents);
+  });
+};
diff --git a/toolkit/components/osfile/tests/xpcshell/test_available_free_space.js b/toolkit/components/osfile/tests/xpcshell/test_available_free_space.js
new file mode 100644
index 000000000..08e67763b
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_available_free_space.js
@@ -0,0 +1,38 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+do_register_cleanup(function() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", false);
+});
+
+function run_test() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", true);
+
+  run_next_test();
+}
+
+/**
+ * Test OS.File.getAvailableFreeSpace
+ */
+add_task(function() {
+  // Set up profile. We will use profile path to query for available free
+  // space.
+  do_get_profile();
+
+  let dir = OS.Constants.Path.profileDir;
+
+  // Sanity checking for the test
+  do_check_true((yield OS.File.exists(dir)));
+
+  // Query for available bytes for user
+  let availableBytes = yield OS.File.getAvailableFreeSpace(dir);
+
+  do_check_true(!!availableBytes);
+  do_check_true(availableBytes > 0);
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_compression.js b/toolkit/components/osfile/tests/xpcshell/test_compression.js
new file mode 100644
index 000000000..b40235615
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_compression.js
@@ -0,0 +1,98 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+
+function run_test() {
+  do_test_pending();
+  run_next_test();
+}
+
+add_task(function test_compress_lz4() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir, "compression.lz");
+  let length = 1024;
+  let array = new Uint8Array(length);
+  for (let i = 0; i < array.byteLength; ++i) {
+    array[i] = i;
+  }
+  let arrayAsString = Array.prototype.join.call(array);
+
+  do_print("Writing data with lz4 compression");
+  let bytes = yield OS.File.writeAtomic(path, array, { compression: "lz4" });
+  do_print("Compressed " + length + " bytes into " + bytes);
+
+  do_print("Reading back with lz4 decompression");
+  let decompressed = yield OS.File.read(path, { compression: "lz4" });
+  do_print("Decompressed into " + decompressed.byteLength + " bytes");
+  do_check_eq(arrayAsString, Array.prototype.join.call(decompressed));
+});
+
+add_task(function test_uncompressed() {
+  do_print("Writing data without compression");
+  let path = OS.Path.join(OS.Constants.Path.tmpDir, "no_compression.tmp");
+  let array = new Uint8Array(1024);
+  for (let i = 0; i < array.byteLength; ++i) {
+    array[i] = i;
+  }
+  let bytes = yield OS.File.writeAtomic(path, array); // No compression
+
+  let exn;
+  // Force decompression, reading should fail
+  try {
+    yield OS.File.read(path, { compression: "lz4" });
+  } catch (ex) {
+    exn = ex;
+  }
+  do_check_true(!!exn);
+  // Check the exception message (and that it contains the file name)
+  do_check_true(exn.message.indexOf(`Invalid header (no magic number) - Data: ${ path }`) != -1);
+});
+
+add_task(function test_no_header() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir, "no_header.tmp");
+  let array = new Uint8Array(8).fill(0,0);  // Small array with no header
+
+  do_print("Writing data with no header");
+
+  let bytes = yield OS.File.writeAtomic(path, array); // No compression
+  let exn;
+  // Force decompression, reading should fail
+  try {
+    yield OS.File.read(path, { compression: "lz4" });
+  } catch (ex) {
+    exn = ex;
+  }
+  do_check_true(!!exn);
+  // Check the exception message (and that it contains the file name)
+  do_check_true(exn.message.indexOf(`Buffer is too short (no header) - Data: ${ path }`) != -1);
+});
+
+add_task(function test_invalid_content() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir, "invalid_content.tmp");
+  let arr1 = new Uint8Array([109, 111, 122, 76, 122, 52, 48, 0]);
+  let arr2 = new Uint8Array(248).fill(1,0);
+
+  let array = new Uint8Array(arr1.length + arr2.length);
+  array.set(arr1);
+  array.set(arr2, arr1.length);
+
+  do_print("Writing invalid data (with a valid header and only ones after that)");
+
+  let bytes = yield OS.File.writeAtomic(path, array); // No compression
+  let exn;
+  // Force decompression, reading should fail
+  try {
+    yield OS.File.read(path, { compression: "lz4" });
+  } catch (ex) {
+    exn = ex;
+  }
+  do_check_true(!!exn);
+  // Check the exception message (and that it contains the file name)
+  do_check_true(exn.message.indexOf(`Invalid content: Decompression stopped at 0 - Data: ${ path }`) != -1);
+});
+
+add_task(function() {
+  do_test_finished();
+});
\ No newline at end of file
diff --git a/toolkit/components/osfile/tests/xpcshell/test_constants.js b/toolkit/components/osfile/tests/xpcshell/test_constants.js
new file mode 100644
index 000000000..e92f33ab8
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_constants.js
@@ -0,0 +1,31 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm", this);
+
+function run_test() {
+  run_next_test();
+}
+
+// Test that OS.Constants is defined correctly.
+add_task(function* check_definition() {
+  do_check_true(OS.Constants!=null);
+  do_check_true(!!OS.Constants.Win || !!OS.Constants.libc);
+  do_check_true(OS.Constants.Path!=null);
+  do_check_true(OS.Constants.Sys!=null);
+  //check system name
+  if (OS.Constants.Sys.Name == "Gonk") {
+  // Services.appinfo.OS doesn't know the difference between Gonk and Android
+    do_check_eq(Services.appinfo.OS, "Android");
+  } else {
+    do_check_eq(Services.appinfo.OS, OS.Constants.Sys.Name);
+  }
+
+  //check if using DEBUG build
+  if (Components.classes["@mozilla.org/xpcom/debug;1"].getService(Components.interfaces.nsIDebug2).isDebugBuild == true) {
+    do_check_true(OS.Constants.Sys.DEBUG);
+  } else {
+    do_check_true(typeof(OS.Constants.Sys.DEBUG) == 'undefined');
+  }
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_creationDate.js b/toolkit/components/osfile/tests/xpcshell/test_creationDate.js
new file mode 100644
index 000000000..9c4fa1dfc
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_creationDate.js
@@ -0,0 +1,31 @@
+"use strict";
+
+function run_test() {
+  do_test_pending();
+  run_next_test();
+}
+
+/**
+ * Test to ensure that deprecation warning is issued on use
+ * of creationDate.
+ */
+add_task(function test_deprecatedCreationDate () {
+  let deferred = Promise.defer();
+  let consoleListener = {
+    observe: function (aMessage) {
+      if(aMessage.message.indexOf("Field 'creationDate' is deprecated.") > -1) {
+        do_print("Deprecation message printed");
+        do_check_true(true);
+        Services.console.unregisterListener(consoleListener);
+        deferred.resolve();
+      }
+    }
+  };
+  let currentDir = yield OS.File.getCurrentDirectory();
+  let path = OS.Path.join(currentDir, "test_creationDate.js");
+
+  Services.console.registerListener(consoleListener);
+  (yield OS.File.stat(path)).creationDate;
+});
+
+add_task(do_test_finished);
diff --git a/toolkit/components/osfile/tests/xpcshell/test_duration.js b/toolkit/components/osfile/tests/xpcshell/test_duration.js
new file mode 100644
index 000000000..305c03da8
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_duration.js
@@ -0,0 +1,91 @@
+var {OS} = Components.utils.import("resource://gre/modules/osfile.jsm", {});
+var {Services} = Components.utils.import("resource://gre/modules/Services.jsm", {});
+
+/**
+ * Test optional duration reporting that can be used for telemetry.
+ */
+add_task(function* duration() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", true);
+  // Options structure passed to a OS.File copy method.
+  let copyOptions = {
+    // This field should be overridden with the actual duration
+    // measurement.
+    outExecutionDuration: null
+  };
+  let currentDir = yield OS.File.getCurrentDirectory();
+  let pathSource = OS.Path.join(currentDir, "test_duration.js");
+  let copyFile = pathSource + ".bak";
+  function testOptions(options, name) {
+    do_print("Checking outExecutionDuration for operation: " + name);
+    do_print(name + ": Gathered method duration time: " +
+      options.outExecutionDuration + "ms");
+    // Making sure that duration was updated.
+    do_check_eq(typeof options.outExecutionDuration, "number");
+    do_check_true(options.outExecutionDuration >= 0);
+  };
+  // Testing duration of OS.File.copy.
+  yield OS.File.copy(pathSource, copyFile, copyOptions);
+  testOptions(copyOptions, "OS.File.copy");
+  yield OS.File.remove(copyFile);
+
+  // Trying an operation where options are cloned.
+  let pathDest = OS.Path.join(OS.Constants.Path.tmpDir,
+    "osfile async test read writeAtomic.tmp");
+  let tmpPath = pathDest + ".tmp";
+  let readOptions = {
+    outExecutionDuration: null
+  };
+  let contents = yield OS.File.read(pathSource, undefined, readOptions);
+  testOptions(readOptions, "OS.File.read");
+  // Options structure passed to a OS.File writeAtomic method.
+  let writeAtomicOptions = {
+    // This field should be first initialized with the actual
+    // duration measurement then progressively incremented.
+    outExecutionDuration: null,
+    tmpPath: tmpPath
+  };
+  yield OS.File.writeAtomic(pathDest, contents, writeAtomicOptions);
+  testOptions(writeAtomicOptions, "OS.File.writeAtomic");
+  yield OS.File.remove(pathDest);
+
+  do_print("Ensuring that we can use outExecutionDuration to accumulate durations");
+
+  let ARBITRARY_BASE_DURATION = 5;
+  copyOptions = {
+    // This field should now be incremented with the actual duration
+    // measurement.
+    outExecutionDuration: ARBITRARY_BASE_DURATION
+  };
+  let backupDuration = ARBITRARY_BASE_DURATION;
+  // Testing duration of OS.File.copy.
+  yield OS.File.copy(pathSource, copyFile, copyOptions);
+
+  do_check_true(copyOptions.outExecutionDuration >= backupDuration);
+
+  backupDuration = copyOptions.outExecutionDuration;
+  yield OS.File.remove(copyFile, copyOptions);
+  do_check_true(copyOptions.outExecutionDuration >= backupDuration);
+
+  // Trying an operation where options are cloned.
+  // Options structure passed to a OS.File writeAtomic method.
+  writeAtomicOptions = {
+    // This field should be overridden with the actual duration
+    // measurement.
+    outExecutionDuration: copyOptions.outExecutionDuration,
+    tmpPath: tmpPath
+  };
+  backupDuration = writeAtomicOptions.outExecutionDuration;
+
+  yield OS.File.writeAtomic(pathDest, contents, writeAtomicOptions);
+  do_check_true(copyOptions.outExecutionDuration >= backupDuration);
+  OS.File.remove(pathDest);
+
+  // Testing an operation that doesn't take arguments at all
+  let file = yield OS.File.open(pathSource);
+  yield file.stat();
+  yield file.close();
+});
+
+function run_test() {
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_exception.js b/toolkit/components/osfile/tests/xpcshell/test_exception.js
new file mode 100644
index 000000000..1282adb3e
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_exception.js
@@ -0,0 +1,89 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Test that functions throw the appropriate exceptions.
+ */
+
+"use strict";
+
+var EXISTING_FILE = do_get_file("xpcshell.ini").path;
+
+
+// Tests on |open|
+
+add_test_pair(function test_typeerror() {
+  let exn;
+  try {
+    let fd = yield OS.File.open("/tmp", {no_such_key: 1});
+    do_print("Fd: " + fd);
+  } catch (ex) {
+    exn = ex;
+  }
+  do_print("Exception: " + exn);
+  do_check_true(exn.constructor.name == "TypeError");
+});
+
+// Tests on |read|
+
+add_test_pair(function* test_bad_encoding() {
+  do_print("Testing with a wrong encoding");
+  try {
+    yield OS.File.read(EXISTING_FILE, { encoding: "baby-speak-encoded" });
+    do_throw("Should have thrown with an ex.becauseInvalidArgument");
+  } catch (ex if ex.becauseInvalidArgument) {
+    do_print("Wrong encoding caused the correct exception");
+  }
+
+  try {
+    yield OS.File.read(EXISTING_FILE, { encoding: 4 });
+    do_throw("Should have thrown a TypeError");
+  } catch (ex if ex.constructor.name == "TypeError") {
+    // Note that TypeError doesn't carry across compartments
+    do_print("Non-string encoding caused the correct exception");
+  }
+ });
+
+add_test_pair(function* test_bad_compression() {
+  do_print("Testing with a non-existing compression");
+  try {
+    yield OS.File.read(EXISTING_FILE, { compression: "mmmh-crunchy" });
+    do_throw("Should have thrown with an ex.becauseInvalidArgument");
+  } catch (ex if ex.becauseInvalidArgument) {
+    do_print("Wrong encoding caused the correct exception");
+  }
+
+  do_print("Testing with a bad type for option compression");
+  try {
+    yield OS.File.read(EXISTING_FILE, { compression: 5 });
+    do_throw("Should have thrown a TypeError");
+  } catch (ex if ex.constructor.name == "TypeError") {
+    // Note that TypeError doesn't carry across compartments
+    do_print("Non-string encoding caused the correct exception");
+  }
+});
+
+add_test_pair(function* test_bad_bytes() {
+  do_print("Testing with a bad type for option bytes");
+  try {
+    yield OS.File.read(EXISTING_FILE, { bytes: "five" });
+    do_throw("Should have thrown a TypeError");
+  } catch (ex if ex.constructor.name == "TypeError") {
+    // Note that TypeError doesn't carry across compartments
+    do_print("Non-number bytes caused the correct exception");
+  }
+});
+
+add_test_pair(function* read_non_existent() {
+  do_print("Testing with a non-existent file");
+  try {
+    yield OS.File.read("I/do/not/exist");
+    do_throw("Should have thrown with an ex.becauseNoSuchFile");
+  } catch (ex if ex.becauseNoSuchFile) {
+    do_print("Correct exceptions");
+  }
+});
+
+function run_test() {
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_file_URL_conversion.js b/toolkit/components/osfile/tests/xpcshell/test_file_URL_conversion.js
new file mode 100644
index 000000000..3ec42065b
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_file_URL_conversion.js
@@ -0,0 +1,114 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+function run_test() {
+  Components.utils.import("resource://gre/modules/Services.jsm");
+  Components.utils.import("resource://gre/modules/osfile.jsm");
+  Components.utils.import("resource://gre/modules/FileUtils.jsm");
+
+  let isWindows = ("@mozilla.org/windows-registry-key;1" in Components.classes);
+
+  // Test cases for filePathToURI
+  let paths = isWindows ? [
+    'C:\\',
+    'C:\\test',
+    'C:\\test\\',
+    'C:\\test%2f',
+    'C:\\test\\test\\test',
+    'C:\\test;+%',
+    'C:\\test?action=index\\',
+    'C:\\test\ test',
+    '\\\\C:\\a\\b\\c',
+    '\\\\Server\\a\\b\\c',
+
+    // note that per http://support.microsoft.com/kb/177506 (under more info),
+    // the following characters are allowed on Windows:
+    'C:\\char^',
+    'C:\\char&',
+    'C:\\char\'',
+    'C:\\char@',
+    'C:\\char{',
+    'C:\\char}',
+    'C:\\char[',
+    'C:\\char]',
+    'C:\\char,',
+    'C:\\char$',
+    'C:\\char=',
+    'C:\\char!',
+    'C:\\char-',
+    'C:\\char#',
+    'C:\\char(',
+    'C:\\char)',
+    'C:\\char%',
+    'C:\\char.',
+    'C:\\char+',
+    'C:\\char~',
+    'C:\\char_'
+  ] : [
+    '/',
+    '/test',
+    '/test/',
+    '/test%2f',
+    '/test/test/test',
+    '/test;+%',
+    '/test?action=index/',
+    '/test\ test',
+    '/punctuation/;,/?:@&=+$-_.!~*\'()[]"#',
+    '/CasePreserving'
+  ];
+
+  // some additional URIs to test, beyond those generated from paths
+  let uris = isWindows ? [
+    'file:///C:/test/',
+    'file://localhost/C:/test',
+    'file:///c:/test/test.txt',
+    //'file:///C:/foo%2f', // trailing, encoded slash
+    'file:///C:/%3f%3F',
+    'file:///C:/%3b%3B',
+    'file:///C:/%3c%3C', // not one of the special-cased ? or ;
+    'file:///C:/%78', // 'x', not usually uri encoded
+    'file:///C:/test#frag', // a fragment identifier
+    'file:///C:/test?action=index' // an actual query component
+  ] : [
+    'file:///test/',
+    'file://localhost/test',
+    'file:///test/test.txt',
+    'file:///foo%2f', // trailing, encoded slash
+    'file:///%3f%3F',
+    'file:///%3b%3B',
+    'file:///%3c%3C', // not one of the special-cased ? or ;
+    'file:///%78', // 'x', not usually uri encoded
+    'file:///test#frag', // a fragment identifier
+    'file:///test?action=index' // an actual query component
+  ];
+
+  for (let path of paths) {
+    // convert that to a uri using FileUtils and Services, which toFileURI is trying to model
+    let file = FileUtils.File(path);
+    let uri = Services.io.newFileURI(file).spec;
+    do_check_eq(uri, OS.Path.toFileURI(path));
+
+    // keep the resulting URI to try the reverse, except for "C:\" for which the
+    // behavior of nsIFileURL and OS.File is inconsistent
+    if (path != "C:\\") {
+      uris.push(uri);
+    }
+  }
+
+  for (let uri of uris) {
+    // convert URIs to paths with nsIFileURI, which fromFileURI is trying to model
+    let path = Services.io.newURI(uri, null, null).QueryInterface(Components.interfaces.nsIFileURL).file.path;
+    do_check_eq(path, OS.Path.fromFileURI(uri));
+  }
+
+  // check that non-file URLs aren't allowed
+  let thrown = false;
+  try {
+    OS.Path.fromFileURI('http://test.com')
+  } catch (e) {
+    do_check_eq(e.message, "fromFileURI expects a file URI");
+    thrown = true;
+  }
+  do_check_true(thrown);
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_loader.js b/toolkit/components/osfile/tests/xpcshell/test_loader.js
new file mode 100644
index 000000000..dcfa819be
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_loader.js
@@ -0,0 +1,37 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that OS.File can be loaded using the CommonJS loader.
+ */
+
+var { Loader } = Components.utils.import('resource://gre/modules/commonjs/toolkit/loader.js', {});
+
+function run_test() {
+  run_next_test();
+}
+
+
+add_task(function*() {
+  let dataDir = Services.io.newFileURI(do_get_file("test_loader/", true)).spec + "/";
+  let loader = Loader.Loader({
+    paths: {'': dataDir }
+  });
+
+  let require = Loader.Require(loader, Loader.Module('module_test_loader', 'foo'));
+  do_print("Require is ready");
+  try {
+    require('module_test_loader');
+  } catch (error) {
+    dump('Bootstrap error: ' +
+         (error.message ? error.message : String(error)) + '\n' +
+         (error.stack || error.fileName + ': ' + error.lineNumber) + '\n');
+
+    throw error;
+  }
+
+  do_print("Require has worked");
+});
+
diff --git a/toolkit/components/osfile/tests/xpcshell/test_loader/module_test_loader.js b/toolkit/components/osfile/tests/xpcshell/test_loader/module_test_loader.js
new file mode 100644
index 000000000..18356d6ad
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_loader/module_test_loader.js
@@ -0,0 +1,9 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Load OS.File from a module loaded with the CommonJS/addon-sdk loader
+
+var {Cu} = require("chrome");
+Cu.import('resource://gre/modules/osfile.jsm');
diff --git a/toolkit/components/osfile/tests/xpcshell/test_logging.js b/toolkit/components/osfile/tests/xpcshell/test_logging.js
new file mode 100644
index 000000000..133909e0b
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_logging.js
@@ -0,0 +1,74 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+/**
+ * Tests logging by passing OS.Shared.LOG both an object with its own
+ * toString method, and one with the default.
+ */
+function run_test() {
+  do_test_pending();
+  let messageCount = 0;
+
+  do_print("Test starting");
+
+  // Create a console listener.
+  let consoleListener = {
+    observe: function (aMessage) {
+      //Ignore unexpected messages.
+      if (!(aMessage instanceof Components.interfaces.nsIConsoleMessage)) {
+        return;
+      }
+      // This is required, as printing to the |Services.console|
+      // while in the observe function causes an exception.
+      do_execute_soon(function() {
+        do_print("Observing message " + aMessage.message);
+        if (aMessage.message.indexOf("TEST OS") < 0) {
+          return;
+        }
+
+        ++messageCount;
+        if(messageCount == 1) {
+          do_check_eq(aMessage.message, "TEST OS {\"name\":\"test\"}\n");
+        }
+        if(messageCount == 2) {
+          do_check_eq(aMessage.message, "TEST OS name is test\n");
+          toggleConsoleListener(false);
+          do_test_finished();
+        }
+      });
+    }
+  };
+
+  // Set/Unset the console listener.
+  function toggleConsoleListener (pref) {
+    do_print("Setting console listener: " + pref);
+    Services.prefs.setBoolPref("toolkit.osfile.log", pref);
+    Services.prefs.setBoolPref("toolkit.osfile.log.redirect", pref);
+    Services.console[pref ? "registerListener" : "unregisterListener"](
+      consoleListener);
+  }
+
+  toggleConsoleListener(true);
+
+  let objectDefault = {name: "test"};
+  let CustomToString = function() {
+    this.name = "test";
+  };
+  CustomToString.prototype.toString = function() {
+    return "name is " + this.name;
+  };
+  let objectCustom = new CustomToString();
+
+  do_print(OS.Shared.LOG.toSource());
+
+  do_print("Logging 1");
+  OS.Shared.LOG(objectDefault);
+
+  do_print("Logging 2");
+  OS.Shared.LOG(objectCustom);
+  // Once both messages are observed OS.Shared.DEBUG, and OS.Shared.TEST
+  // are reset to false.
+}
+
diff --git a/toolkit/components/osfile/tests/xpcshell/test_makeDir.js b/toolkit/components/osfile/tests/xpcshell/test_makeDir.js
new file mode 100644
index 000000000..5b9740a7f
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_makeDir.js
@@ -0,0 +1,142 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+var Path = OS.Path;
+var profileDir;
+
+do_register_cleanup(function() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", false);
+});
+
+function run_test() {
+  run_next_test();
+}
+
+/**
+ * Test OS.File.makeDir
+ */
+
+add_task(function init() {
+  // Set up profile. We create the directory in the profile, because the profile
+  // is removed after every test run.
+  do_get_profile();
+  profileDir = OS.Constants.Path.profileDir;
+  Services.prefs.setBoolPref("toolkit.osfile.log", true);
+});
+
+/**
+ * Basic use
+ */
+
+add_task(function* test_basic() {
+  let dir = Path.join(profileDir, "directory");
+
+  // Sanity checking for the test
+  do_check_false((yield OS.File.exists(dir)));
+
+  // Make a directory
+  yield OS.File.makeDir(dir);
+
+  //check if the directory exists
+  yield OS.File.stat(dir);
+
+  // Make a directory that already exists, this should succeed
+  yield OS.File.makeDir(dir);
+
+  // Make a directory with ignoreExisting
+  yield OS.File.makeDir(dir, {ignoreExisting: true});
+
+  // Make a directory with ignoreExisting false
+  let exception = null;
+  try {
+    yield OS.File.makeDir(dir, {ignoreExisting: false});
+  } catch (ex) {
+    exception = ex;
+  }
+
+  do_check_true(!!exception);
+  do_check_true(exception instanceof OS.File.Error);
+  do_check_true(exception.becauseExists);
+});
+
+// Make a root directory that already exists
+add_task(function* test_root() {
+  if (OS.Constants.Win) {
+    yield OS.File.makeDir("C:");
+    yield OS.File.makeDir("C:\\");
+  } else {
+    yield OS.File.makeDir("/");
+  }
+});
+
+/**
+ * Creating subdirectories
+ */
+add_task(function test_option_from() {
+  let dir = Path.join(profileDir, "a", "b", "c");
+
+  // Sanity checking for the test
+  do_check_false((yield OS.File.exists(dir)));
+
+  // Make a directory
+  yield OS.File.makeDir(dir, {from: profileDir});
+
+  //check if the directory exists
+  yield OS.File.stat(dir);
+
+  // Make a directory that already exists, this should succeed
+  yield OS.File.makeDir(dir);
+
+  // Make a directory with ignoreExisting
+  yield OS.File.makeDir(dir, {ignoreExisting: true});
+
+  // Make a directory with ignoreExisting false
+  let exception = null;
+  try {
+    yield OS.File.makeDir(dir, {ignoreExisting: false});
+  } catch (ex) {
+    exception = ex;
+  }
+
+  do_check_true(!!exception);
+  do_check_true(exception instanceof OS.File.Error);
+  do_check_true(exception.becauseExists);
+
+  // Make a directory without |from| and fail
+  let dir2 = Path.join(profileDir, "g", "h", "i");
+  exception = null;
+  try {
+    yield OS.File.makeDir(dir2);
+  } catch (ex) {
+    exception = ex;
+  }
+
+  do_check_true(!!exception);
+  do_check_true(exception instanceof OS.File.Error);
+  do_check_true(exception.becauseNoSuchFile);
+
+  // Test edge cases on paths
+
+  let dir3 = Path.join(profileDir, "d", "", "e", "f");
+  do_check_false((yield OS.File.exists(dir3)));
+  yield OS.File.makeDir(dir3, {from: profileDir});
+  do_check_true((yield OS.File.exists(dir3)));
+
+  let dir4;
+  if (OS.Constants.Win) {
+    // Test that we can create a directory recursively even
+    // if we have too many "\\".
+    dir4 = profileDir + "\\\\g";
+  } else {
+    dir4 = profileDir + "////g";
+  }
+  do_check_false((yield OS.File.exists(dir4)));
+  yield OS.File.makeDir(dir4, {from: profileDir});
+  do_check_true((yield OS.File.exists(dir4)));
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_open.js b/toolkit/components/osfile/tests/xpcshell/test_open.js
new file mode 100644
index 000000000..78772ad09
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_open.js
@@ -0,0 +1,70 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+
+function run_test() {
+  run_next_test();
+}
+
+/**
+ * Test OS.File.open for reading:
+ * - with an existing file (should succeed);
+ * - with a non-existing file (should fail);
+ * - with inconsistent arguments (should fail).
+ */
+add_task(function() {
+  // Attempt to open a file that does not exist, ensure that it yields the
+  // appropriate error.
+  try {
+    let fd = yield OS.File.open(OS.Path.join(".", "This file does not exist"));
+    do_check_true(false, "File opening 1 succeeded (it should fail)");
+  } catch (err if err instanceof OS.File.Error && err.becauseNoSuchFile) {
+    do_print("File opening 1 failed " + err);
+  }
+
+  // Attempt to open a file with the wrong args, so that it fails before
+  // serialization, ensure that it yields the appropriate error.
+  do_print("Attempting to open a file with wrong arguments");
+  try {
+    let fd = yield OS.File.open(1, 2, 3);
+    do_check_true(false, "File opening 2 succeeded (it should fail)" + fd);
+  } catch (err) {
+    do_print("File opening 2 failed " + err);
+    do_check_false(err instanceof OS.File.Error,
+                   "File opening 2 returned something that is not a file error");
+    do_check_true(err.constructor.name == "TypeError",
+                  "File opening 2 returned a TypeError");
+  }
+
+  // Attempt to open a file correctly
+  do_print("Attempting to open a file correctly");
+  let openedFile = yield OS.File.open(OS.Path.join(do_get_cwd().path, "test_open.js"));
+  do_print("File opened correctly");
+
+  do_print("Attempting to close a file correctly");
+  yield openedFile.close();
+
+  do_print("Attempting to close a file again");
+  yield openedFile.close();
+});
+
+/**
+ * Test the error thrown by OS.File.open when attempting to open a directory
+ * that does not exist.
+ */
+add_task(function test_error_attributes () {
+
+  let dir = OS.Path.join(do_get_profile().path, "test_osfileErrorAttrs");
+  let fpath = OS.Path.join(dir, "test_error_attributes.txt");
+
+  try {
+    yield OS.File.open(fpath, {truncate: true}, {});
+    do_check_true(false, "Opening path suceeded (it should fail) " + fpath);
+  } catch (err) {
+    do_check_true(err instanceof OS.File.Error);
+    do_check_true(err.becauseNoSuchFile);
+  }
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_async.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_async.js
new file mode 100644
index 000000000..0f86b2ea8
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_async.js
@@ -0,0 +1,16 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+
+/**
+ * A trivial test ensuring that we can call osfile from xpcshell.
+ * (see bug 808161)
+ */
+
+function run_test() {
+  do_test_pending();
+  OS.File.getCurrentDirectory().then(
+    do_test_finished,
+    do_test_finished
+  );
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_async_append.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_append.js
new file mode 100644
index 000000000..0aef2c58a
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_append.js
@@ -0,0 +1,122 @@
+"use strict";
+
+do_print("starting tests");
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+/**
+ * A test to check that the |append| mode flag is correctly implemented.
+ * (see bug 925865)
+ */
+
+function setup_mode(mode) {
+  // Complete mode.
+  let realMode = {
+    read: true,
+    write: true
+  };
+  for (let k in mode) {
+    realMode[k] = mode[k];
+  }
+  return realMode;
+}
+
+// Test append mode.
+function test_append(mode) {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_async_append.tmp");
+
+  // Clear any left-over files from previous runs.
+  try {
+    yield OS.File.remove(path);
+  } catch (ex if ex.becauseNoSuchFile) {
+    // ignore
+  }
+
+  try {
+    mode = setup_mode(mode);
+    mode.append = true;
+    if (mode.trunc) {
+      // Pre-fill file with some data to see if |trunc| actually works.
+      yield OS.File.writeAtomic(path, new Uint8Array(500));
+    }
+    let file = yield OS.File.open(path, mode);
+    try {
+      yield file.write(new Uint8Array(1000));
+      yield file.setPosition(0, OS.File.POS_START);
+      yield file.read(100);
+      // Should be at offset 100, length 1000 now.
+      yield file.write(new Uint8Array(100));
+      // Should be at offset 1100, length 1100 now.
+      let stat = yield file.stat();
+      do_check_eq(1100, stat.size);
+    } finally {
+      yield file.close();
+    }
+  } catch(ex) {
+    try {
+      yield OS.File.remove(path);
+    } catch (ex if ex.becauseNoSuchFile) {
+      // ignore.
+    }
+  }
+}
+
+// Test no-append mode.
+function test_no_append(mode) {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_async_noappend.tmp");
+
+  // Clear any left-over files from previous runs.
+  try {
+    yield OS.File.remove(path);
+  } catch (ex if ex.becauseNoSuchFile) {
+    // ignore
+  }
+
+  try {
+    mode = setup_mode(mode);
+    mode.append = false;
+    if (mode.trunc) {
+      // Pre-fill file with some data to see if |trunc| actually works.
+      yield OS.File.writeAtomic(path, new Uint8Array(500));
+    }
+    let file = yield OS.File.open(path, mode);
+    try {
+      yield file.write(new Uint8Array(1000));
+      yield file.setPosition(0, OS.File.POS_START);
+      yield file.read(100);
+      // Should be at offset 100, length 1000 now.
+      yield file.write(new Uint8Array(100));
+      // Should be at offset 200, length 1000 now.
+      let stat = yield file.stat();
+      do_check_eq(1000, stat.size);
+    } finally {
+      yield file.close();
+    }
+  } finally {
+    try {
+      yield OS.File.remove(path);
+    } catch (ex if ex.becauseNoSuchFile) {
+      // ignore.
+    }
+  }
+}
+
+var test_flags = [
+  {},
+  {create:true},
+  {trunc:true}
+];
+function run_test() {
+  do_test_pending();
+
+  for (let t of test_flags) {
+    add_task(test_append.bind(null, t));
+    add_task(test_no_append.bind(null, t));
+  }
+  add_task(do_test_finished);
+
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_async_bytes.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_bytes.js
new file mode 100644
index 000000000..68fa9152c
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_bytes.js
@@ -0,0 +1,39 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+function run_test() {
+  do_test_pending();
+  run_next_test();
+}
+
+/**
+ * Test to ensure that {bytes:} in options to |write| is correctly
+ * preserved.
+ */
+add_task(function* test_bytes() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_async_bytes.tmp");
+  let file = yield OS.File.open(path, {trunc: true, read: true, write: true});
+  try {
+    try {
+      // 1. Test write, by supplying {bytes:} options smaller than the actual
+      // buffer.
+      yield file.write(new Uint8Array(2048), {bytes: 1024});
+      do_check_eq((yield file.stat()).size, 1024);
+
+      // 2. Test that passing nullish values for |options| still works.
+      yield file.setPosition(0, OS.File.POS_END);
+      yield file.write(new Uint8Array(1024), null);
+      yield file.write(new Uint8Array(1024), undefined);
+      do_check_eq((yield file.stat()).size, 3072);
+    } finally {
+      yield file.close();
+    }
+  } finally {
+    yield OS.File.remove(path);
+  }
+});
+
+add_task(do_test_finished);
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_async_copy.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_copy.js
new file mode 100644
index 000000000..9c52c8a80
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_copy.js
@@ -0,0 +1,113 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/FileUtils.jsm");
+Components.utils.import("resource://gre/modules/NetUtil.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+Components.utils.import("resource://gre/modules/Promise.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+function run_test() {
+  do_test_pending();
+  run_next_test();
+}
+
+/**
+ * A file that we know exists and that can be used for reading.
+ */
+var EXISTING_FILE = "test_osfile_async_copy.js";
+
+/**
+ * Fetch asynchronously the contents of a file using xpcom.
+ *
+ * Used for comparing xpcom-based results to os.file-based results.
+ *
+ * @param {string} path The _absolute_ path to the file.
+ * @return {promise}
+ * @resolves {string} The contents of the file.
+ */
+var reference_fetch_file = function reference_fetch_file(path) {
+  let promise = Promise.defer();
+  let file = new FileUtils.File(path);
+  NetUtil.asyncFetch({
+    uri: NetUtil.newURI(file),
+    loadUsingSystemPrincipal: true
+  }, function(stream, status) {
+      if (!Components.isSuccessCode(status)) {
+        promise.reject(status);
+        return;
+      }
+      let result, reject;
+      try {
+        result = NetUtil.readInputStreamToString(stream, stream.available());
+      } catch (x) {
+        reject = x;
+      }
+      stream.close();
+      if (reject) {
+        promise.reject(reject);
+      } else {
+        promise.resolve(result);
+      }
+    });
+
+  return promise.promise;
+};
+
+/**
+ * Compare asynchronously the contents two files using xpcom.
+ *
+ * Used for comparing xpcom-based results to os.file-based results.
+ *
+ * @param {string} a The _absolute_ path to the first file.
+ * @param {string} b The _absolute_ path to the second file.
+ *
+ * @resolves {null}
+ */
+var reference_compare_files = function reference_compare_files(a, b) {
+  let a_contents = yield reference_fetch_file(a);
+  let b_contents = yield reference_fetch_file(b);
+  // Not using do_check_eq to avoid dumping the whole file to the log.
+  // It is OK to === compare here, as both variables contain a string.
+  do_check_true(a_contents === b_contents);
+};
+
+/**
+ * Test to ensure that OS.File.copy works.
+ */
+function test_copymove(options = {}) {
+  let source = OS.Path.join((yield OS.File.getCurrentDirectory()),
+                            EXISTING_FILE);
+  let dest = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_async_copy_dest.tmp");
+  let dest2 = OS.Path.join(OS.Constants.Path.tmpDir,
+                           "test_osfile_async_copy_dest2.tmp");
+  try {
+    // 1. Test copy.
+    yield OS.File.copy(source, dest, options);
+    yield reference_compare_files(source, dest);
+    // 2. Test subsequent move.
+    yield OS.File.move(dest, dest2);
+    yield reference_compare_files(source, dest2);
+    // 3. Check that the moved file was really moved.
+    do_check_eq((yield OS.File.exists(dest)), false);
+  } finally {
+    try {
+      yield OS.File.remove(dest);
+    } catch (ex if ex.becauseNoSuchFile) {
+      // ignore
+    }
+    try {
+      yield OS.File.remove(dest2);
+    } catch (ex if ex.becauseNoSuchFile) {
+      // ignore
+    }
+  }
+}
+
+// Regular copy test.
+add_task(test_copymove);
+// Userland copy test.
+add_task(test_copymove.bind(null, {unixUserland: true}));
+
+add_task(do_test_finished);
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_async_flush.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_flush.js
new file mode 100644
index 000000000..9ed087f4e
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_flush.js
@@ -0,0 +1,30 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+function run_test() {
+  do_test_pending();
+  run_next_test();
+}
+
+/**
+ * Test to ensure that |File.prototype.flush| is available in the async API.
+ */
+
+add_task(function test_flush() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_async_flush.tmp");
+  let file = yield OS.File.open(path, {trunc: true, write: true});
+  try {
+    try {
+      yield file.flush();
+    } finally {
+      yield file.close();
+    }
+  } finally {
+    yield OS.File.remove(path);
+  }
+});
+
+add_task(do_test_finished);
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_async_largefiles.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_largefiles.js
new file mode 100644
index 000000000..a9ac776b0
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_largefiles.js
@@ -0,0 +1,153 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/ctypes.jsm");
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+/**
+ * A test to check that .getPosition/.setPosition work with large files.
+ * (see bug 952997)
+ */
+
+// Test setPosition/getPosition.
+function test_setPosition(forward, current, backward) {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_async_largefiles.tmp");
+
+  // Clear any left-over files from previous runs.
+  try {
+    yield OS.File.remove(path);
+  } catch (ex if ex.becauseNoSuchFile) {
+    // ignore
+  }
+
+  try {
+    let file = yield OS.File.open(path, {write:true, append:false});
+    try {
+      let pos = 0;
+
+      // 1. seek forward from start
+      do_print("Moving forward: " + forward);
+      yield file.setPosition(forward, OS.File.POS_START);
+      pos += forward;
+      do_check_eq((yield file.getPosition()), pos);
+
+      // 2. seek forward from current position
+      do_print("Moving current: " + current);
+      yield file.setPosition(current, OS.File.POS_CURRENT);
+      pos += current;
+      do_check_eq((yield file.getPosition()), pos);
+
+      // 3. seek backward from current position
+      do_print("Moving current backward: " + backward);
+      yield file.setPosition(-backward, OS.File.POS_CURRENT);
+      pos -= backward;
+      do_check_eq((yield file.getPosition()), pos);
+
+    } finally {
+      yield file.setPosition(0, OS.File.POS_START);
+      yield file.close();
+    }
+  } catch(ex) {
+    try {
+      yield OS.File.remove(path);
+    } catch (ex if ex.becauseNoSuchFile) {
+      // ignore.
+    }
+    do_throw(ex);
+  }
+}
+
+// Test setPosition/getPosition expected failures.
+function test_setPosition_failures() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_async_largefiles.tmp");
+
+  // Clear any left-over files from previous runs.
+  try {
+    yield OS.File.remove(path);
+  } catch (ex if ex.becauseNoSuchFile) {
+    // ignore
+  }
+
+  try {
+    let file = yield OS.File.open(path, {write:true, append:false});
+    try {
+      let pos = 0;
+
+      // 1. Use an invalid position value
+      try {
+        yield file.setPosition(0.5, OS.File.POS_START);
+        do_throw("Shouldn't have succeeded");
+      } catch (ex) {
+        do_check_true(ex.toString().includes("can't pass"));
+      }
+      // Since setPosition should have bailed, it shouldn't have moved the
+      // file pointer at all.
+      do_check_eq((yield file.getPosition()), 0);
+
+      // 2. Use an invalid position value
+      try {
+        yield file.setPosition(0xffffffff + 0.5, OS.File.POS_START);
+        do_throw("Shouldn't have succeeded");
+      } catch (ex) {
+        do_check_true(ex.toString().includes("can't pass"));
+      }
+      // Since setPosition should have bailed, it shouldn't have moved the
+      // file pointer at all.
+      do_check_eq((yield file.getPosition()), 0);
+
+      // 3. Use a position that cannot be represented as a double
+      try {
+        // Not all numbers after 9007199254740992 can be represented as a
+        // double. E.g. in js 9007199254740992 + 1 == 9007199254740992
+        yield file.setPosition(9007199254740992, OS.File.POS_START);
+        yield file.setPosition(1, OS.File.POS_CURRENT);
+        do_throw("Shouldn't have succeeded");
+      } catch (ex) {
+        do_print(ex.toString());
+        do_check_true(!!ex);
+      }
+
+    } finally {
+      yield file.setPosition(0, OS.File.POS_START);
+      yield file.close();
+      try {
+        yield OS.File.remove(path);
+      } catch (ex if ex.becauseNoSuchFile) {
+        // ignore.
+      }
+    }
+  } catch(ex) {
+    do_throw(ex);
+  }
+}
+
+function run_test() {
+  // First verify stuff works for small values.
+  add_task(test_setPosition.bind(null, 0, 100, 50));
+  add_task(test_setPosition.bind(null, 1000, 100, 50));
+  add_task(test_setPosition.bind(null, 1000, -100, -50));
+
+  if (OS.Constants.Win || ctypes.off_t.size >= 8) {
+    // Now verify stuff still works for large values.
+    // 1. Multiple small seeks, which add up to > MAXINT32
+    add_task(test_setPosition.bind(null, 0x7fffffff, 0x7fffffff, 0));
+    // 2. Plain large seek, that should end up at 0 again.
+    // 0xffffffff also happens to be the INVALID_SET_FILE_POINTER value on
+    // Windows, so this also tests the error handling
+    add_task(test_setPosition.bind(null, 0, 0xffffffff, 0xffffffff));
+    // 3. Multiple large seeks that should end up > MAXINT32.
+    add_task(test_setPosition.bind(null, 0xffffffff, 0xffffffff, 0xffffffff));
+    // 5. Multiple large seeks with negative offsets.
+    add_task(test_setPosition.bind(null, 0xffffffff, -0x7fffffff, 0x7fffffff));
+
+    // 6. Check failures
+    add_task(test_setPosition_failures);
+  }
+
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_async_setDates.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_setDates.js
new file mode 100644
index 000000000..17d3afa7c
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_setDates.js
@@ -0,0 +1,211 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+/**
+ * A test to ensure that OS.File.setDates and OS.File.prototype.setDates are
+ * working correctly.
+ * (see bug 924916)
+ */
+
+function run_test() {
+  run_next_test();
+}
+
+// Non-prototypical tests, operating on path names.
+add_task(function* test_nonproto() {
+  // First, create a file we can mess with.
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                              "test_osfile_async_setDates_nonproto.tmp");
+  yield OS.File.writeAtomic(path, new Uint8Array(1));
+
+  try {
+    // 1. Try to set some well known dates.
+    // We choose multiples of 2000ms, because the time stamp resolution of
+    // the underlying OS might not support something more precise.
+    const accDate = 2000;
+    const modDate = 4000;
+    {
+      yield OS.File.setDates(path, accDate, modDate);
+      let stat = yield OS.File.stat(path);
+      do_check_eq(accDate, stat.lastAccessDate.getTime());
+      do_check_eq(modDate, stat.lastModificationDate.getTime());
+    }
+
+    // 2.1 Try to omit modificationDate (which should then default to
+    // |Date.now()|, expect for resolution differences).
+    {
+      yield OS.File.setDates(path, accDate);
+      let stat = yield OS.File.stat(path);
+      do_check_eq(accDate, stat.lastAccessDate.getTime());
+      do_check_neq(modDate, stat.lastModificationDate.getTime());
+    }
+
+    // 2.2 Try to omit accessDate as well (which should then default to
+    // |Date.now()|, expect for resolution differences).
+    {
+      yield OS.File.setDates(path);
+      let stat = yield OS.File.stat(path);
+      do_check_neq(accDate, stat.lastAccessDate.getTime());
+      do_check_neq(modDate, stat.lastModificationDate.getTime());
+    }
+
+    // 3. Repeat 1., but with Date objects this time
+    {
+      yield OS.File.setDates(path, new Date(accDate), new Date(modDate));
+      let stat = yield OS.File.stat(path);
+      do_check_eq(accDate, stat.lastAccessDate.getTime());
+      do_check_eq(modDate, stat.lastModificationDate.getTime());
+    }
+
+    // 4. Check that invalid params will cause an exception/rejection.
+    {
+      for (let p of ["invalid", new Uint8Array(1), NaN]) {
+        try {
+          yield OS.File.setDates(path, p, modDate);
+          do_throw("Invalid access date should have thrown for: " + p);
+        } catch (ex) {
+          let stat = yield OS.File.stat(path);
+          do_check_eq(accDate, stat.lastAccessDate.getTime());
+          do_check_eq(modDate, stat.lastModificationDate.getTime());
+        }
+        try {
+          yield OS.File.setDates(path, accDate, p);
+          do_throw("Invalid modification date should have thrown for: " + p);
+        } catch (ex) {
+          let stat = yield OS.File.stat(path);
+          do_check_eq(accDate, stat.lastAccessDate.getTime());
+          do_check_eq(modDate, stat.lastModificationDate.getTime());
+        }
+        try {
+          yield OS.File.setDates(path, p, p);
+          do_throw("Invalid dates should have thrown for: " + p);
+        } catch (ex) {
+          let stat = yield OS.File.stat(path);
+          do_check_eq(accDate, stat.lastAccessDate.getTime());
+          do_check_eq(modDate, stat.lastModificationDate.getTime());
+        }
+      }
+    }
+  } finally {
+    // Remove the temp file again
+    yield OS.File.remove(path);
+  }
+});
+
+// Prototypical tests, operating on |File| handles.
+add_task(function* test_proto() {
+  if (OS.Constants.Sys.Name == "Android" || OS.Constants.Sys.Name == "Gonk") {
+    do_print("File.prototype.setDates is not implemented for Android/B2G");
+    do_check_eq(OS.File.prototype.setDates, undefined);
+    return;
+  }
+
+  // First, create a file we can mess with.
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                              "test_osfile_async_setDates_proto.tmp");
+  yield OS.File.writeAtomic(path, new Uint8Array(1));
+
+  try {
+    let fd = yield OS.File.open(path, {write: true});
+
+    try {
+      // 1. Try to set some well known dates.
+      // We choose multiples of 2000ms, because the time stamp resolution of
+      // the underlying OS might not support something more precise.
+      const accDate = 2000;
+      const modDate = 4000;
+      {
+        yield fd.setDates(accDate, modDate);
+        let stat = yield fd.stat();
+        do_check_eq(accDate, stat.lastAccessDate.getTime());
+        do_check_eq(modDate, stat.lastModificationDate.getTime());
+      }
+
+      // 2.1 Try to omit modificationDate (which should then default to
+      // |Date.now()|, expect for resolution differences).
+      {
+        yield fd.setDates(accDate);
+        let stat = yield fd.stat();
+        do_check_eq(accDate, stat.lastAccessDate.getTime());
+        do_check_neq(modDate, stat.lastModificationDate.getTime());
+      }
+
+      // 2.2 Try to omit accessDate as well (which should then default to
+      // |Date.now()|, expect for resolution differences).
+      {
+        yield fd.setDates();
+        let stat = yield fd.stat();
+        do_check_neq(accDate, stat.lastAccessDate.getTime());
+        do_check_neq(modDate, stat.lastModificationDate.getTime());
+      }
+
+      // 3. Repeat 1., but with Date objects this time
+      {
+        yield fd.setDates(new Date(accDate), new Date(modDate));
+        let stat = yield fd.stat();
+        do_check_eq(accDate, stat.lastAccessDate.getTime());
+        do_check_eq(modDate, stat.lastModificationDate.getTime());
+      }
+
+      // 4. Check that invalid params will cause an exception/rejection.
+      {
+        for (let p of ["invalid", new Uint8Array(1), NaN]) {
+          try {
+            yield fd.setDates(p, modDate);
+            do_throw("Invalid access date should have thrown for: " + p);
+          } catch (ex) {
+            let stat = yield fd.stat();
+            do_check_eq(accDate, stat.lastAccessDate.getTime());
+            do_check_eq(modDate, stat.lastModificationDate.getTime());
+          }
+          try {
+            yield fd.setDates(accDate, p);
+            do_throw("Invalid modification date should have thrown for: " + p);
+          } catch (ex) {
+            let stat = yield fd.stat();
+            do_check_eq(accDate, stat.lastAccessDate.getTime());
+            do_check_eq(modDate, stat.lastModificationDate.getTime());
+          }
+          try {
+            yield fd.setDates(p, p);
+            do_throw("Invalid dates should have thrown for: " + p);
+          } catch (ex) {
+            let stat = yield fd.stat();
+            do_check_eq(accDate, stat.lastAccessDate.getTime());
+            do_check_eq(modDate, stat.lastModificationDate.getTime());
+          }
+        }
+      }
+    } finally {
+      yield fd.close();
+    }
+  } finally {
+    // Remove the temp file again
+    yield OS.File.remove(path);
+  }
+});
+
+// Tests setting dates on directories.
+add_task(function* test_dirs() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                              "test_osfile_async_setDates_dir");
+  yield OS.File.makeDir(path);
+
+  try {
+    // 1. Try to set some well known dates.
+    // We choose multiples of 2000ms, because the time stamp resolution of
+    // the underlying OS might not support something more precise.
+    const accDate = 2000;
+    const modDate = 4000;
+    {
+      yield OS.File.setDates(path, accDate, modDate);
+      let stat = yield OS.File.stat(path);
+      do_check_eq(accDate, stat.lastAccessDate.getTime());
+      do_check_eq(modDate, stat.lastModificationDate.getTime());
+    }
+  } finally {
+    yield OS.File.removeEmptyDir(path);
+  }
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_async_setPermissions.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_setPermissions.js
new file mode 100644
index 000000000..ab8bf7dd9
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_async_setPermissions.js
@@ -0,0 +1,103 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * A test to ensure that OS.File.setPermissions and
+ * OS.File.prototype.setPermissions are all working correctly.
+ * (see bug 1001849)
+ * These functions are currently Unix-specific.  The manifest skips
+ * the test on Windows.
+ */
+
+/**
+ * Helper function for test logging: prints a POSIX file permission mode as an
+ * octal number, with a leading '0' per C (not JS) convention.  When the
+ * numeric value is 0o777 or lower, it is padded on the left with zeroes to
+ * four digits wide.
+ * Sample outputs:  0022, 0644, 04755.
+ */
+function format_mode(mode) {
+  if (mode <= 0o777) {
+    return ("0000" + mode.toString(8)).slice(-4);
+  } else {
+    return "0" + mode.toString(8);
+  }
+}
+
+const _umask = OS.Constants.Sys.umask;
+do_print("umask: " + format_mode(_umask));
+
+/**
+ * Compute the mode that a file should have after applying the umask,
+ * whatever it happens to be.
+ */
+function apply_umask(mode) {
+  return mode & ~_umask;
+}
+
+// Sequence of setPermission parameters and expected file mode.  The first test
+// checks the permissions when the file is first created.
+var testSequence = [
+  [null,                                        apply_umask(0o600)],
+  [{ unixMode: 0o4777 },                        apply_umask(0o4777)],
+  [{ unixMode: 0o4777, unixHonorUmask: false }, 0o4777],
+  [{ unixMode: 0o4777, unixHonorUmask: true },  apply_umask(0o4777)],
+  [undefined,                                   apply_umask(0o600)],
+  [{ unixMode: 0o666 },                         apply_umask(0o666)],
+  [{ unixMode: 0o600 },                         apply_umask(0o600)],
+  [{ unixMode: 0 },                             0],
+  [{},                                          apply_umask(0o600)],
+];
+
+// Test application to paths.
+add_task(function* test_path_setPermissions() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_async_setPermissions_path.tmp");
+  yield OS.File.writeAtomic(path, new Uint8Array(1));
+
+  try {
+    for (let [options, expectedMode] of testSequence) {
+      if (options !== null) {
+        do_print("Setting permissions to " + JSON.stringify(options));
+        yield OS.File.setPermissions(path, options);
+      }
+
+      let stat = yield OS.File.stat(path);
+      do_check_eq(format_mode(stat.unixMode), format_mode(expectedMode));
+    }
+  } finally {
+    yield OS.File.remove(path);
+  }
+});
+
+// Test application to open files.
+add_task(function* test_file_setPermissions() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                              "test_osfile_async_setPermissions_file.tmp");
+  yield OS.File.writeAtomic(path, new Uint8Array(1));
+
+  try {
+    let fd = yield OS.File.open(path, { write: true });
+    try {
+      for (let [options, expectedMode] of testSequence) {
+        if (options !== null) {
+          do_print("Setting permissions to " + JSON.stringify(options));
+          yield fd.setPermissions(options);
+        }
+
+        let stat = yield fd.stat();
+        do_check_eq(format_mode(stat.unixMode), format_mode(expectedMode));
+      }
+    } finally {
+      yield fd.close();
+    }
+  } finally {
+    yield OS.File.remove(path);
+  }
+});
+
+function run_test() {
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_closed.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_closed.js
new file mode 100644
index 000000000..5740f7f1a
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_closed.js
@@ -0,0 +1,48 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+function run_test() {
+  do_test_pending();
+  run_next_test();
+}
+
+add_task(function test_closed() {
+  OS.Shared.DEBUG = true;
+  let currentDir = yield OS.File.getCurrentDirectory();
+  do_print("Open a file, ensure that we can call stat()");
+  let path = OS.Path.join(currentDir, "test_osfile_closed.js");
+  let file = yield OS.File.open(path);
+  yield file.stat();
+  do_check_true(true);
+
+  yield file.close();
+
+  do_print("Ensure that we cannot stat() on closed file");
+  let exn;
+  try {
+    yield file.stat();
+  } catch (ex) {
+    exn = ex;
+  }
+  do_print("Ensure that this raises the correct error");
+  do_check_true(!!exn);
+  do_check_true(exn instanceof OS.File.Error);
+  do_check_true(exn.becauseClosed);
+
+  do_print("Ensure that we cannot read() on closed file");
+  exn = null;
+  try {
+    yield file.read();
+  } catch (ex) {
+    exn = ex;
+  }
+  do_print("Ensure that this raises the correct error");
+  do_check_true(!!exn);
+  do_check_true(exn instanceof OS.File.Error);
+  do_check_true(exn.becauseClosed);
+
+});
+
+add_task(do_test_finished);
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_error.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_error.js
new file mode 100644
index 000000000..a1c319eca
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_error.js
@@ -0,0 +1,63 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+var {OS: {File, Path, Constants}} = Components.utils.import("resource://gre/modules/osfile.jsm", {});
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+function run_test() {
+  run_next_test();
+}
+
+add_task(function* testFileError_with_writeAtomic() {
+  let DEFAULT_CONTENTS = "default contents" + Math.random();
+  let path = Path.join(Constants.Path.tmpDir,
+                       "testFileError.tmp");
+  yield File.remove(path);
+  yield File.writeAtomic(path, DEFAULT_CONTENTS);
+  let exception;
+  try {
+    yield File.writeAtomic(path, DEFAULT_CONTENTS, { noOverwrite: true });
+  } catch (ex) {
+    exception = ex;
+  }
+  do_check_true(exception instanceof File.Error);
+  do_check_true(exception.path == path);
+});
+
+add_task(function* testFileError_with_makeDir() {
+  let path = Path.join(Constants.Path.tmpDir,
+                       "directory");
+  yield File.removeDir(path);
+  yield File.makeDir(path);
+  let exception;
+  try {
+    yield File.makeDir(path, { ignoreExisting: false });
+  } catch (ex) {
+    exception = ex;
+  }
+  do_check_true(exception instanceof File.Error);
+  do_check_true(exception.path == path);
+});
+
+add_task(function* testFileError_with_move() {
+  let DEFAULT_CONTENTS = "default contents" + Math.random();
+  let sourcePath = Path.join(Constants.Path.tmpDir,
+                             "src.tmp");
+  let destPath = Path.join(Constants.Path.tmpDir,
+                           "dest.tmp");
+  yield File.remove(sourcePath);
+  yield File.remove(destPath);
+  yield File.writeAtomic(sourcePath, DEFAULT_CONTENTS);
+  yield File.writeAtomic(destPath, DEFAULT_CONTENTS);
+  let exception;
+  try {
+    yield File.move(sourcePath, destPath, { noOverwrite: true });
+  } catch (ex) {
+    exception = ex;
+  }
+  do_print(exception);
+  do_check_true(exception instanceof File.Error);
+  do_check_true(exception.path == sourcePath);
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_kill.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_kill.js
new file mode 100644
index 000000000..e32c37224
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_kill.js
@@ -0,0 +1,100 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+
+// We want the actual global to get at the internals since Scheduler is not
+// exported.
+var AsyncFrontGlobal = Components.utils.import(
+                         "resource://gre/modules/osfile/osfile_async_front.jsm",
+                          null);
+var Scheduler = AsyncFrontGlobal.Scheduler;
+
+/**
+ * Verify that Scheduler.kill() interacts with other OS.File requests correctly,
+ * and that no requests are lost.  This is relevant because on B2G we
+ * auto-kill the worker periodically, making it very possible for valid requests
+ * to be interleaved with the automatic kill().
+ *
+ * This test is being created with the fix for Bug 1125989 where `kill` queue
+ * management was found to be buggy.  It is a glass-box test that explicitly
+ * re-creates the observed failure situation; it is not guaranteed to prevent
+ * all future regressions.  The following is a detailed explanation of the test
+ * for your benefit if this test ever breaks or you are wondering what was the
+ * point of all this.  You might want to skim the code below first.
+ *
+ * OS.File maintains a `queue` of operations to be performed.  This queue is
+ * nominally implemented as a chain of promises.  Every time a new job is
+ * OS.File.push()ed, it effectively becomes the new `queue` promise.  (An
+ * extra promise is interposed with a rejection handler to avoid the rejection
+ * cascading, but that does not matter for our purposes.)
+ *
+ * The flaw in `kill` was that it would wait for the `queue` to complete before
+ * replacing `queue`.  As a result, another OS.File operation could use `push`
+ * (by way of OS.File.post()) to also use .then() on the same `queue` promise.
+ * Accordingly, assuming that promise was not yet resolved (due to a pending
+ * OS.File request), when it was resolved, both the task scheduled in `kill`
+ * and in `post` would be triggered.  Both of those tasks would run until
+ * encountering a call to worker.post().
+ *
+ * Re-creating this race is not entirely trivial because of the large number of
+ * promises used by the code causing control flow to repeatedly be deferred.  In
+ * a slightly simpler world we could run the follwing in the same turn of the
+ * event loop and trigger the problem.
+ * - any OS.File request
+ * - Scheduler.kill()
+ * - any OS.File request
+ *
+ * However, we need the Scheduler.kill task to reach the point where it is
+ * waiting on the same `queue` that another task has been scheduled against.
+ * Since the `kill` task yields on the `killQueue` promise prior to yielding
+ * on `queue`, however, some turns of the event loop are required.  Happily,
+ * for us, as discussed above, the problem triggers when we have two promises
+ * scheduled on the `queue`, so we can just wait to schedule the second OS.File
+ * request on the queue.  (Note that because of the additional then() added to
+ * eat rejections, there is an important difference between the value of
+ * `queue` and the value returned by the first OS.File request.)
+ */
+add_task(function* test_kill_race() {
+  // Ensure the worker has been created and that SET_DEBUG has taken effect.
+  // We have chosen OS.File.exists for our tests because it does not trigger
+  // a rejection and we absolutely do not care what the operation is other
+  // than it does not invoke a native fast-path.
+  yield OS.File.exists('foo.foo');
+
+  do_print('issuing first request');
+  let firstRequest = OS.File.exists('foo.bar');
+  let secondRequest;
+  let secondResolved = false;
+
+  // As noted in our big block comment, we want to wait to schedule the
+  // second request so that it races `kill`'s call to `worker.post`.  Having
+  // ourselves wait on the same promise, `queue`, and registering ourselves
+  // before we issue the kill request means we will get run before the `kill`
+  // task resumes and allow us to precisely create the desired race.
+  Scheduler.queue.then(function() {
+    do_print('issuing second request');
+    secondRequest = OS.File.exists('foo.baz');
+    secondRequest.then(function() {
+      secondResolved = true;
+    });
+  });
+
+  do_print('issuing kill request');
+  let killRequest = Scheduler.kill({ reset: true, shutdown: false });
+
+  // Wait on the killRequest so that we can schedule a new OS.File request
+  // after it completes...
+  yield killRequest;
+  // ...because our ordering guarantee ensures that there is at most one
+  // worker (and this usage here should not be vulnerable even with the
+  // bug present), so when this completes the secondRequest has either been
+  // resolved or lost.
+  yield OS.File.exists('foo.goz');
+
+  ok(secondResolved,
+     'The second request was resolved so we avoided the bug. Victory!');
+});
+
+function run_test() {
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_win_async_setPermissions.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_win_async_setPermissions.js
new file mode 100644
index 000000000..990d722f5
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_win_async_setPermissions.js
@@ -0,0 +1,114 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * A test to ensure that OS.File.setPermissions and
+ * OS.File.prototype.setPermissions are all working correctly.
+ * (see bug 1022816)
+ * The manifest tests on Windows.
+ */
+
+// Sequence of setPermission parameters.
+var testSequence = [
+  [ { winAttributes: { readOnly: true, system: true, hidden: true } },
+    { readOnly: true, system: true, hidden: true } ],
+  [ { winAttributes: { readOnly: false } },
+    { readOnly: false, system: true, hidden: true } ],
+  [ { winAttributes: { system: false } },
+    { readOnly: false, system: false, hidden: true } ],
+  [ { winAttributes: { hidden: false } },
+    { readOnly: false, system: false, hidden: false } ],
+  [ { winAttributes: {readOnly: true, system: false, hidden: false} },
+    { readOnly: true, system: false, hidden: false } ],
+  [ { winAttributes: {readOnly: false, system: true, hidden: false} },
+    { readOnly: false, system: true, hidden: false } ],
+  [ { winAttributes: {readOnly: false, system: false, hidden: true} },
+    { readOnly: false, system: false, hidden: true } ],
+];
+
+// Test application to paths.
+add_task(function* test_path_setPermissions() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_win_async_setPermissions_path.tmp");
+  yield OS.File.writeAtomic(path, new Uint8Array(1));
+
+  try {
+    for (let [options, attributesExpected] of testSequence) {
+      if (options !== null) {
+        do_print("Setting permissions to " + JSON.stringify(options));
+        yield OS.File.setPermissions(path, options);
+      }
+
+      let stat = yield OS.File.stat(path);
+      do_print("Got stat winAttributes: " + JSON.stringify(stat.winAttributes));
+
+      do_check_eq(stat.winAttributes.readOnly, attributesExpected.readOnly);
+      do_check_eq(stat.winAttributes.system, attributesExpected.system);
+      do_check_eq(stat.winAttributes.hidden, attributesExpected.hidden);
+
+    }
+  } finally {
+    yield OS.File.remove(path);
+  }
+});
+
+// Test application to open files.
+add_task(function* test_file_setPermissions() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                              "test_osfile_win_async_setPermissions_file.tmp");
+  yield OS.File.writeAtomic(path, new Uint8Array(1));
+
+  try {
+    let fd = yield OS.File.open(path, { write: true });
+    try {
+      for (let [options, attributesExpected] of testSequence) {
+        if (options !== null) {
+          do_print("Setting permissions to " + JSON.stringify(options));
+          yield fd.setPermissions(options);
+        }
+
+        let stat = yield fd.stat();
+        do_print("Got stat winAttributes: " + JSON.stringify(stat.winAttributes));
+        do_check_eq(stat.winAttributes.readOnly, attributesExpected.readOnly);
+        do_check_eq(stat.winAttributes.system, attributesExpected.system);
+        do_check_eq(stat.winAttributes.hidden, attributesExpected.hidden);
+      }
+    } finally {
+      yield fd.close();
+    }
+  } finally {
+    yield OS.File.remove(path);
+  }
+});
+
+// Test application to Check setPermissions on a non-existant file path.
+add_task(function* test_non_existant_file_path_setPermissions() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_win_async_setPermissions_path.tmp");
+  Assert.rejects(OS.File.setPermissions(path, {winAttributes: {readOnly: true}}),
+                 /The system cannot find the file specified/,
+                 "setPermissions failed as expected on a non-existant file path");
+});
+
+// Test application to Check setPermissions on a invalid file handle.
+add_task(function* test_closed_file_handle_setPermissions() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir,
+                          "test_osfile_win_async_setPermissions_path.tmp");
+  yield OS.File.writeAtomic(path, new Uint8Array(1));
+
+  try {
+    let fd = yield OS.File.open(path, { write: true });
+    yield fd.close();
+    Assert.rejects(fd.setPermissions(path, {winAttributes: {readOnly: true}}),
+                   /The handle is invalid/,
+                   "setPermissions failed as expected on a invalid file handle");
+  } finally {
+    yield OS.File.remove(path);
+  }
+});
+
+function run_test() {
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_writeAtomic_backupTo_option.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_writeAtomic_backupTo_option.js
new file mode 100644
index 000000000..adf345b0c
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_writeAtomic_backupTo_option.js
@@ -0,0 +1,143 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+var {OS: {File, Path, Constants}} = Components.utils.import("resource://gre/modules/osfile.jsm", {});
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+/**
+ * Remove all temporary files and back up files, including
+ * test_backupTo_option_with_tmpPath.tmp
+ * test_backupTo_option_with_tmpPath.tmp.backup
+ * test_backupTo_option_without_tmpPath.tmp
+ * test_backupTo_option_without_tmpPath.tmp.backup
+ * test_non_backupTo_option.tmp
+ * test_non_backupTo_option.tmp.backup
+ * test_backupTo_option_without_destination_file.tmp
+ * test_backupTo_option_without_destination_file.tmp.backup
+ * test_backupTo_option_with_backup_file.tmp
+ * test_backupTo_option_with_backup_file.tmp.backup
+ */
+function clearFiles() {
+  return Task.spawn(function () {
+    let files = ["test_backupTo_option_with_tmpPath.tmp",
+                  "test_backupTo_option_without_tmpPath.tmp",
+                  "test_non_backupTo_option.tmp",
+                  "test_backupTo_option_without_destination_file.tmp",
+                  "test_backupTo_option_with_backup_file.tmp"];
+    for (let file of files) {
+      let path = Path.join(Constants.Path.tmpDir, file);
+      yield File.remove(path);
+      yield File.remove(path + ".backup");
+    }
+  });
+}
+
+function run_test() {
+  run_next_test();
+}
+
+add_task(function* init() {
+  yield clearFiles();
+});
+
+/**
+ * test when
+ * |backupTo| specified
+ * |tmpPath| specified
+ * destination file exists
+ * @result destination file will be backed up
+ */
+add_task(function* test_backupTo_option_with_tmpPath() {
+  let DEFAULT_CONTENTS = "default contents" + Math.random();
+  let WRITE_CONTENTS = "abc" + Math.random();
+  let path = Path.join(Constants.Path.tmpDir,
+                       "test_backupTo_option_with_tmpPath.tmp");
+  yield File.writeAtomic(path, DEFAULT_CONTENTS);
+  yield File.writeAtomic(path, WRITE_CONTENTS, { tmpPath: path + ".tmp",
+                                        backupTo: path + ".backup" });
+  do_check_true((yield File.exists(path + ".backup")));
+  let contents = yield File.read(path + ".backup");
+  do_check_eq(DEFAULT_CONTENTS, (new TextDecoder()).decode(contents));
+});
+
+/**
+ * test when
+ * |backupTo| specified
+ * |tmpPath| not specified
+ * destination file exists
+ * @result destination file will be backed up
+ */
+add_task(function* test_backupTo_option_without_tmpPath() {
+  let DEFAULT_CONTENTS = "default contents" + Math.random();
+  let WRITE_CONTENTS = "abc" + Math.random();
+  let path = Path.join(Constants.Path.tmpDir,
+                       "test_backupTo_option_without_tmpPath.tmp");
+  yield File.writeAtomic(path, DEFAULT_CONTENTS);
+  yield File.writeAtomic(path, WRITE_CONTENTS, { backupTo: path + ".backup" });
+  do_check_true((yield File.exists(path + ".backup")));
+  let contents = yield File.read(path + ".backup");
+  do_check_eq(DEFAULT_CONTENTS, (new TextDecoder()).decode(contents));
+});
+
+/**
+ * test when
+ * |backupTo| not specified
+ * |tmpPath| not specified
+ * destination file exists
+ * @result destination file will not be backed up
+ */
+add_task(function* test_non_backupTo_option() {
+  let DEFAULT_CONTENTS = "default contents" + Math.random();
+  let WRITE_CONTENTS = "abc" + Math.random();
+  let path = Path.join(Constants.Path.tmpDir,
+                       "test_non_backupTo_option.tmp");
+  yield File.writeAtomic(path, DEFAULT_CONTENTS);
+  yield File.writeAtomic(path, WRITE_CONTENTS);
+  do_check_false((yield File.exists(path + ".backup")));
+});
+
+/**
+ * test when
+ * |backupTo| specified
+ * |tmpPath| not specified
+ * destination file not exists
+ * @result no back up file exists
+ */
+add_task(function* test_backupTo_option_without_destination_file() {
+  let DEFAULT_CONTENTS = "default contents" + Math.random();
+  let WRITE_CONTENTS = "abc" + Math.random();
+  let path = Path.join(Constants.Path.tmpDir,
+                       "test_backupTo_option_without_destination_file.tmp");
+  yield File.remove(path);
+  yield File.writeAtomic(path, WRITE_CONTENTS, { backupTo: path + ".backup" });
+  do_check_false((yield File.exists(path + ".backup")));
+});
+
+/**
+ * test when
+ * |backupTo| specified
+ * |tmpPath| not specified
+ * backup file exists
+ * destination file exists
+ * @result destination file will be backed up
+ */
+add_task(function* test_backupTo_option_with_backup_file() {
+  let DEFAULT_CONTENTS = "default contents" + Math.random();
+  let WRITE_CONTENTS = "abc" + Math.random();
+  let path = Path.join(Constants.Path.tmpDir,
+                       "test_backupTo_option_with_backup_file.tmp");
+  yield File.writeAtomic(path, DEFAULT_CONTENTS);
+
+  yield File.writeAtomic(path + ".backup", new Uint8Array(1000));
+
+  yield File.writeAtomic(path, WRITE_CONTENTS, { backupTo: path + ".backup" });
+  do_check_true((yield File.exists(path + ".backup")));
+  let contents = yield File.read(path + ".backup");
+  do_check_eq(DEFAULT_CONTENTS, (new TextDecoder()).decode(contents));
+});
+
+add_task(function* cleanup() {
+  yield clearFiles();
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_osfile_writeAtomic_zerobytes.js b/toolkit/components/osfile/tests/xpcshell/test_osfile_writeAtomic_zerobytes.js
new file mode 100644
index 000000000..a32a690e6
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_osfile_writeAtomic_zerobytes.js
@@ -0,0 +1,27 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+var SHARED_PATH;
+
+add_task(function* init() {
+  do_get_profile();
+  SHARED_PATH = OS.Path.join(OS.Constants.Path.profileDir, "test_osfile_write_zerobytes.tmp");
+});
+
+add_test_pair(function* test_osfile_writeAtomic_zerobytes() {
+  let encoder = new TextEncoder();
+  let string1 = "";
+  let outbin = encoder.encode(string1);
+  yield OS.File.writeAtomic(SHARED_PATH, outbin);
+
+  let decoder = new TextDecoder();
+  let bin = yield OS.File.read(SHARED_PATH);
+  let string2 = decoder.decode(bin);
+  // Checking if writeAtomic supports writing encoded zero-byte strings
+  Assert.equal(string2, string1, "Read the expected (empty) string.");
+});
+
+function run_test() {
+  run_next_test();
+}
\ No newline at end of file
diff --git a/toolkit/components/osfile/tests/xpcshell/test_path.js b/toolkit/components/osfile/tests/xpcshell/test_path.js
new file mode 100644
index 000000000..76a507ee3
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_path.js
@@ -0,0 +1,159 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/Services.jsm", this);
+Services.prefs.setBoolPref("toolkit.osfile.test.syslib_necessary", false);
+  // We don't need libc/kernel32.dll for this test
+
+var ImportWin = {};
+var ImportUnix = {};
+Components.utils.import("resource://gre/modules/osfile/ospath_win.jsm", ImportWin);
+Components.utils.import("resource://gre/modules/osfile/ospath_unix.jsm", ImportUnix);
+
+var Win = ImportWin;
+var Unix = ImportUnix;
+
+function do_check_fail(f)
+{
+  try {
+    let result = f();
+    do_print("Failed do_check_fail: " + result);
+    do_check_true(false);
+  } catch (ex) {
+    do_check_true(true);
+  }
+};
+
+function run_test()
+{
+  do_print("Testing Windows paths");
+
+  do_print("Backslash-separated, no drive");
+  do_check_eq(Win.basename("a\\b"), "b");
+  do_check_eq(Win.basename("a\\b\\"), "");
+  do_check_eq(Win.basename("abc"), "abc");
+  do_check_eq(Win.dirname("a\\b"), "a");
+  do_check_eq(Win.dirname("a\\b\\"), "a\\b");
+  do_check_eq(Win.dirname("a\\\\\\\\b"), "a");
+  do_check_eq(Win.dirname("abc"), ".");
+  do_check_eq(Win.normalize("\\a\\b\\c"), "\\a\\b\\c");
+  do_check_eq(Win.normalize("\\a\\b\\\\\\\\c"), "\\a\\b\\c");
+  do_check_eq(Win.normalize("\\a\\b\\c\\\\\\"), "\\a\\b\\c");
+  do_check_eq(Win.normalize("\\a\\b\\c\\..\\..\\..\\d\\e\\f"), "\\d\\e\\f");
+  do_check_eq(Win.normalize("a\\b\\c\\..\\..\\..\\d\\e\\f"), "d\\e\\f");
+  do_check_fail(() => Win.normalize("\\a\\b\\c\\..\\..\\..\\..\\d\\e\\f"));
+
+  do_check_eq(Win.join("\\tmp", "foo", "bar"), "\\tmp\\foo\\bar", "join \\tmp,foo,bar");
+  do_check_eq(Win.join("\\tmp", "\\foo", "bar"), "\\foo\\bar", "join \\tmp,\\foo,bar");
+  do_check_eq(Win.winGetDrive("\\tmp"), null);
+  do_check_eq(Win.winGetDrive("\\tmp\\a\\b\\c\\d\\e"), null);
+  do_check_eq(Win.winGetDrive("\\"), null);
+
+
+  do_print("Backslash-separated, with a drive");
+  do_check_eq(Win.basename("c:a\\b"), "b");
+  do_check_eq(Win.basename("c:a\\b\\"), "");
+  do_check_eq(Win.basename("c:abc"), "abc");
+  do_check_eq(Win.dirname("c:a\\b"), "c:a");
+  do_check_eq(Win.dirname("c:a\\b\\"), "c:a\\b");
+  do_check_eq(Win.dirname("c:a\\\\\\\\b"), "c:a");
+  do_check_eq(Win.dirname("c:abc"), "c:");
+  let options = {
+    winNoDrive: true
+  };
+  do_check_eq(Win.dirname("c:a\\b", options), "a");
+  do_check_eq(Win.dirname("c:a\\b\\", options), "a\\b");
+  do_check_eq(Win.dirname("c:a\\\\\\\\b", options), "a");
+  do_check_eq(Win.dirname("c:abc", options), ".");
+  do_check_eq(Win.join("c:", "abc"), "c:\\abc", "join c:,abc");
+
+  do_check_eq(Win.normalize("c:"), "c:\\");
+  do_check_eq(Win.normalize("c:\\"), "c:\\");
+  do_check_eq(Win.normalize("c:\\a\\b\\c"), "c:\\a\\b\\c");
+  do_check_eq(Win.normalize("c:\\a\\b\\\\\\\\c"), "c:\\a\\b\\c");
+  do_check_eq(Win.normalize("c:\\\\\\\\a\\b\\c"), "c:\\a\\b\\c");
+  do_check_eq(Win.normalize("c:\\a\\b\\c\\\\\\"), "c:\\a\\b\\c");
+  do_check_eq(Win.normalize("c:\\a\\b\\c\\..\\..\\..\\d\\e\\f"), "c:\\d\\e\\f");
+  do_check_eq(Win.normalize("c:a\\b\\c\\..\\..\\..\\d\\e\\f"), "c:\\d\\e\\f");
+  do_check_fail(() => Win.normalize("c:\\a\\b\\c\\..\\..\\..\\..\\d\\e\\f"));
+
+  do_check_eq(Win.join("c:\\", "foo"), "c:\\foo", "join c:\,foo");
+  do_check_eq(Win.join("c:\\tmp", "foo", "bar"), "c:\\tmp\\foo\\bar", "join c:\\tmp,foo,bar");
+  do_check_eq(Win.join("c:\\tmp", "\\foo", "bar"), "c:\\foo\\bar", "join c:\\tmp,\\foo,bar");
+  do_check_eq(Win.join("c:\\tmp", "c:\\foo", "bar"), "c:\\foo\\bar", "join c:\\tmp,c:\\foo,bar");
+  do_check_eq(Win.join("c:\\tmp", "c:foo", "bar"), "c:\\foo\\bar", "join c:\\tmp,c:foo,bar");
+  do_check_eq(Win.winGetDrive("c:"), "c:");
+  do_check_eq(Win.winGetDrive("c:\\"), "c:");
+  do_check_eq(Win.winGetDrive("c:abc"), "c:");
+  do_check_eq(Win.winGetDrive("c:abc\\d\\e\\f\\g"), "c:");
+  do_check_eq(Win.winGetDrive("c:\\abc"), "c:");
+  do_check_eq(Win.winGetDrive("c:\\abc\\d\\e\\f\\g"), "c:");
+
+  do_print("Forwardslash-separated, no drive");
+  do_check_eq(Win.normalize("/a/b/c"), "\\a\\b\\c");
+  do_check_eq(Win.normalize("/a/b////c"), "\\a\\b\\c");
+  do_check_eq(Win.normalize("/a/b/c///"), "\\a\\b\\c");
+  do_check_eq(Win.normalize("/a/b/c/../../../d/e/f"), "\\d\\e\\f");
+  do_check_eq(Win.normalize("a/b/c/../../../d/e/f"), "d\\e\\f");
+
+  do_print("Forwardslash-separated, with a drive");
+  do_check_eq(Win.normalize("c:/"), "c:\\");
+  do_check_eq(Win.normalize("c:/a/b/c"), "c:\\a\\b\\c");
+  do_check_eq(Win.normalize("c:/a/b////c"), "c:\\a\\b\\c");
+  do_check_eq(Win.normalize("c:////a/b/c"), "c:\\a\\b\\c");
+  do_check_eq(Win.normalize("c:/a/b/c///"), "c:\\a\\b\\c");
+  do_check_eq(Win.normalize("c:/a/b/c/../../../d/e/f"), "c:\\d\\e\\f");
+  do_check_eq(Win.normalize("c:a/b/c/../../../d/e/f"), "c:\\d\\e\\f");
+
+  do_print("Backslash-separated, UNC-style");
+  do_check_eq(Win.basename("\\\\a\\b"), "b");
+  do_check_eq(Win.basename("\\\\a\\b\\"), "");
+  do_check_eq(Win.basename("\\\\abc"), "");
+  do_check_eq(Win.dirname("\\\\a\\b"), "\\\\a");
+  do_check_eq(Win.dirname("\\\\a\\b\\"), "\\\\a\\b");
+  do_check_eq(Win.dirname("\\\\a\\\\\\\\b"), "\\\\a");
+  do_check_eq(Win.dirname("\\\\abc"), "\\\\abc");
+  do_check_eq(Win.normalize("\\\\a\\b\\c"), "\\\\a\\b\\c");
+  do_check_eq(Win.normalize("\\\\a\\b\\\\\\\\c"), "\\\\a\\b\\c");
+  do_check_eq(Win.normalize("\\\\a\\b\\c\\\\\\"), "\\\\a\\b\\c");
+  do_check_eq(Win.normalize("\\\\a\\b\\c\\..\\..\\d\\e\\f"), "\\\\a\\d\\e\\f");
+  do_check_fail(() => Win.normalize("\\\\a\\b\\c\\..\\..\\..\\d\\e\\f"));
+
+  do_check_eq(Win.join("\\\\a\\tmp", "foo", "bar"), "\\\\a\\tmp\\foo\\bar");
+  do_check_eq(Win.join("\\\\a\\tmp", "\\foo", "bar"), "\\\\a\\foo\\bar");
+  do_check_eq(Win.join("\\\\a\\tmp", "\\\\foo\\", "bar"), "\\\\foo\\bar");
+  do_check_eq(Win.winGetDrive("\\\\"), null);
+  do_check_eq(Win.winGetDrive("\\\\c"), "\\\\c");
+  do_check_eq(Win.winGetDrive("\\\\c\\abc"), "\\\\c");
+
+  do_print("Testing unix paths");
+  do_check_eq(Unix.basename("a/b"), "b");
+  do_check_eq(Unix.basename("a/b/"), "");
+  do_check_eq(Unix.basename("abc"), "abc");
+  do_check_eq(Unix.dirname("a/b"), "a");
+  do_check_eq(Unix.dirname("a/b/"), "a/b");
+  do_check_eq(Unix.dirname("a////b"), "a");
+  do_check_eq(Unix.dirname("abc"), ".");
+  do_check_eq(Unix.normalize("/a/b/c"), "/a/b/c");
+  do_check_eq(Unix.normalize("/a/b////c"), "/a/b/c");
+  do_check_eq(Unix.normalize("////a/b/c"), "/a/b/c");
+  do_check_eq(Unix.normalize("/a/b/c///"), "/a/b/c");
+  do_check_eq(Unix.normalize("/a/b/c/../../../d/e/f"), "/d/e/f");
+  do_check_eq(Unix.normalize("a/b/c/../../../d/e/f"), "d/e/f");
+  do_check_fail(() => Unix.normalize("/a/b/c/../../../../d/e/f"));
+
+  do_check_eq(Unix.join("/tmp", "foo", "bar"), "/tmp/foo/bar", "join /tmp,foo,bar");
+  do_check_eq(Unix.join("/tmp", "/foo", "bar"), "/foo/bar", "join /tmp,/foo,bar");
+
+  do_print("Testing the presence of ospath.jsm");
+  let Scope = {};
+  try {
+    Components.utils.import("resource://gre/modules/osfile/ospath.jsm", Scope);
+  } catch (ex) {
+    // Can't load ospath
+  }
+  do_check_true(!!Scope.basename);
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_path_constants.js b/toolkit/components/osfile/tests/xpcshell/test_path_constants.js
new file mode 100644
index 000000000..c0057c750
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_path_constants.js
@@ -0,0 +1,83 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+Cu.import("resource://gre/modules/ctypes.jsm", this);
+Cu.import("resource://testing-common/AppData.jsm", this);
+
+
+function run_test() {
+  run_next_test();
+}
+
+function compare_paths(ospath, key) {
+  let file;
+  try {
+    file = Services.dirsvc.get(key, Components.interfaces.nsIFile);
+  } catch(ex) {}
+
+  if (file) {
+    do_check_true(!!ospath);
+    do_check_eq(ospath, file.path);
+  } else {
+    do_print("WARNING: " + key + " is not defined. Test may not be testing anything!");
+    do_check_false(!!ospath);
+  }
+}
+
+// Some path constants aren't set up until the profile is available. This
+// test verifies that behavior.
+add_task(function* test_before_after_profile() {
+  do_check_null(OS.Constants.Path.profileDir);
+  do_check_null(OS.Constants.Path.localProfileDir);
+  do_check_null(OS.Constants.Path.userApplicationDataDir);
+
+  do_get_profile();
+  do_check_true(!!OS.Constants.Path.profileDir);
+  do_check_true(!!OS.Constants.Path.localProfileDir);
+
+  // UAppData is still null because the xpcshell profile doesn't set it up.
+  // This test is mostly here to fail in case behavior of do_get_profile() ever
+  // changes. We want to know if our assumptions no longer hold!
+  do_check_null(OS.Constants.Path.userApplicationDataDir);
+
+  yield makeFakeAppDir();
+  do_check_true(!!OS.Constants.Path.userApplicationDataDir);
+
+  // FUTURE: verify AppData too (bug 964291).
+});
+
+// Test simple paths
+add_task(function* test_simple_paths() {
+  do_check_true(!!OS.Constants.Path.tmpDir);
+  compare_paths(OS.Constants.Path.tmpDir, "TmpD");
+
+});
+
+// Test presence of paths that only exist on Desktop platforms
+add_task(function* test_desktop_paths() {
+  if (OS.Constants.Sys.Name == "Android" || OS.Constants.Sys.Name == "Gonk") {
+    return;
+  }
+  do_check_true(!!OS.Constants.Path.desktopDir);
+  do_check_true(!!OS.Constants.Path.homeDir);
+
+  compare_paths(OS.Constants.Path.homeDir, "Home");
+  compare_paths(OS.Constants.Path.desktopDir, "Desk");
+  compare_paths(OS.Constants.Path.userApplicationDataDir, "UAppData");
+
+  compare_paths(OS.Constants.Path.winAppDataDir, "AppData");
+  compare_paths(OS.Constants.Path.winStartMenuProgsDir, "Progs");
+
+  compare_paths(OS.Constants.Path.macUserLibDir, "ULibDir");
+  compare_paths(OS.Constants.Path.macLocalApplicationsDir, "LocApp");
+  compare_paths(OS.Constants.Path.macTrashDir, "Trsh");
+});
+
+// Open libxul
+add_task(function* test_libxul() {
+  ctypes.open(OS.Constants.Path.libxul);
+  do_print("Linked to libxul");
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_queue.js b/toolkit/components/osfile/tests/xpcshell/test_queue.js
new file mode 100644
index 000000000..c9d23eabc
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_queue.js
@@ -0,0 +1,38 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+
+function run_test() {
+  run_next_test();
+}
+
+// Check if Scheduler.queue returned by OS.File.queue is resolved initially.
+add_task(function* check_init() {
+  yield OS.File.queue;
+  do_print("Function resolved");
+});
+
+// Check if Scheduler.queue returned by OS.File.queue is resolved
+// after an operation is successful.
+add_task(function* check_success() {
+  do_print("Attempting to open a file correctly");
+  let openedFile = yield OS.File.open(OS.Path.join(do_get_cwd().path, "test_queue.js"));
+  do_print("File opened correctly");
+  yield OS.File.queue;
+  do_print("Function resolved");
+});
+
+// Check if Scheduler.queue returned by OS.File.queue is resolved
+// after an operation fails.
+add_task(function* check_failure() {
+  let exception;
+  try {
+    do_print("Attempting to open a non existing file");
+    yield OS.File.open(OS.Path.join(".", "Bigfoot"));
+  } catch (err) {
+    exception = err;
+    yield OS.File.queue;
+  }  
+  do_check_true(exception!=null);
+  do_print("Function resolved");
+});
\ No newline at end of file
diff --git a/toolkit/components/osfile/tests/xpcshell/test_read_write.js b/toolkit/components/osfile/tests/xpcshell/test_read_write.js
new file mode 100644
index 000000000..00235ed8c
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_read_write.js
@@ -0,0 +1,103 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+var {utils: Cu} = Components;
+
+var SHARED_PATH;
+
+var EXISTING_FILE = do_get_file("xpcshell.ini").path;
+
+add_task(function* init() {
+  do_get_profile();
+  SHARED_PATH = OS.Path.join(OS.Constants.Path.profileDir, "test_osfile_read.tmp");
+});
+
+
+// Check that OS.File.read() is executed after the previous operation
+add_test_pair(function* ordering() {
+  let string1 = "Initial state " + Math.random();
+  let string2 = "After writing " + Math.random();
+  yield OS.File.writeAtomic(SHARED_PATH, string1);
+  OS.File.writeAtomic(SHARED_PATH, string2);
+  let string3 = yield OS.File.read(SHARED_PATH, { encoding: "utf-8" });
+  do_check_eq(string3, string2);
+});
+
+add_test_pair(function* read_write_all() {
+  let DEST_PATH = SHARED_PATH + Math.random();
+  let TMP_PATH = DEST_PATH + ".tmp";
+
+  let test_with_options = function(options, suffix) {
+    return Task.spawn(function*() {
+      do_print("Running test read_write_all with options " + JSON.stringify(options));
+      let TEST = "read_write_all " + suffix;
+
+      let optionsBackup = JSON.parse(JSON.stringify(options));
+
+      // Check that read + writeAtomic performs a correct copy
+      let currentDir = yield OS.File.getCurrentDirectory();
+      let pathSource = OS.Path.join(currentDir, EXISTING_FILE);
+      let contents = yield OS.File.read(pathSource);
+      do_check_true(!!contents); // Content is not empty
+      let bytesRead = contents.byteLength;
+
+      let bytesWritten = yield OS.File.writeAtomic(DEST_PATH, contents, options);
+      do_check_eq(bytesRead, bytesWritten); // Correct number of bytes written
+
+      // Check that options are not altered
+      do_check_eq(JSON.stringify(options), JSON.stringify(optionsBackup));
+      yield reference_compare_files(pathSource, DEST_PATH, TEST);
+
+      // Check that temporary file was removed or never created exist
+      do_check_false(new FileUtils.File(TMP_PATH).exists());
+
+      // Check that writeAtomic fails if noOverwrite is true and the destination
+      // file already exists!
+      contents = new Uint8Array(300);
+      let view = new Uint8Array(contents.buffer, 10, 200);
+      try {
+        let opt = JSON.parse(JSON.stringify(options));
+        opt.noOverwrite = true;
+        yield OS.File.writeAtomic(DEST_PATH, view, opt);
+        do_throw("With noOverwrite, writeAtomic should have refused to overwrite file (" + suffix + ")");
+      } catch (err if err instanceof OS.File.Error && err.becauseExists) {
+        do_print("With noOverwrite, writeAtomic correctly failed (" + suffix + ")");
+      }
+      yield reference_compare_files(pathSource, DEST_PATH, TEST);
+
+      // Check that temporary file was removed or never created
+      do_check_false(new FileUtils.File(TMP_PATH).exists());
+
+      // Now write a subset
+      let START = 10;
+      let LENGTH = 100;
+      contents = new Uint8Array(300);
+      for (var i = 0; i < contents.byteLength; i++)
+        contents[i] = i % 256;
+      view = new Uint8Array(contents.buffer, START, LENGTH);
+      bytesWritten = yield OS.File.writeAtomic(DEST_PATH, view, options);
+      do_check_eq(bytesWritten, LENGTH);
+
+      let array2 = yield OS.File.read(DEST_PATH);
+      do_check_eq(LENGTH, array2.length);
+      for (var i = 0; i < LENGTH; i++)
+        do_check_eq(array2[i], (i + START) % 256);
+
+      // Cleanup.
+      yield OS.File.remove(DEST_PATH);
+      yield OS.File.remove(TMP_PATH);
+    });
+  };
+
+  yield test_with_options({tmpPath: TMP_PATH}, "Renaming, not flushing");
+  yield test_with_options({tmpPath: TMP_PATH, flush: true}, "Renaming, flushing");
+  yield test_with_options({}, "Not renaming, not flushing");
+  yield test_with_options({flush: true}, "Not renaming, flushing");
+});
+
+
+function run_test() {
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_remove.js b/toolkit/components/osfile/tests/xpcshell/test_remove.js
new file mode 100644
index 000000000..c8dc33054
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_remove.js
@@ -0,0 +1,56 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+do_register_cleanup(function() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", false);
+});
+
+function run_test() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", true);
+  run_next_test();
+}
+
+add_task(function* test_ignoreAbsent() {
+  let absent_file_name = "test_osfile_front_absent.tmp";
+
+  // Removing absent files should throw if "ignoreAbsent" is true.
+  yield Assert.rejects(OS.File.remove(absent_file_name, {ignoreAbsent: false}),
+                       "OS.File.remove throws if there is no such file.");
+
+  // Removing absent files should not throw if "ignoreAbsent" is true or not
+  // defined.
+  let exception = null;
+  try {
+    yield OS.File.remove(absent_file_name, {ignoreAbsent: true});
+    yield OS.File.remove(absent_file_name);
+  } catch (ex) {
+    exception = ex;
+  }
+  Assert.ok(!exception, "OS.File.remove should not throw when not requested.");
+});
+
+add_task(function* test_ignoreAbsent_directory_missing() {
+  let absent_file_name = OS.Path.join("absent_parent", "test.tmp");
+
+  // Removing absent files should throw if "ignoreAbsent" is true.
+  yield Assert.rejects(OS.File.remove(absent_file_name, {ignoreAbsent: false}),
+                       "OS.File.remove throws if there is no such file.");
+
+  // Removing files from absent directories should not throw if "ignoreAbsent"
+  // is true or not defined.
+  let exception = null;
+  try {
+    yield OS.File.remove(absent_file_name, {ignoreAbsent: true});
+    yield OS.File.remove(absent_file_name);
+  } catch (ex) {
+    exception = ex;
+  }
+  Assert.ok(!exception, "OS.File.remove should not throw when not requested.");
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_removeDir.js b/toolkit/components/osfile/tests/xpcshell/test_removeDir.js
new file mode 100644
index 000000000..41ad0eb8c
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_removeDir.js
@@ -0,0 +1,177 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+do_register_cleanup(function() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", false);
+});
+
+function run_test() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", true);
+
+  run_next_test();
+}
+
+add_task(function() {
+  // Set up profile. We create the directory in the profile, because the profile
+  // is removed after every test run.
+  do_get_profile();
+
+  let file = OS.Path.join(OS.Constants.Path.profileDir, "file");
+  let dir = OS.Path.join(OS.Constants.Path.profileDir, "directory");
+  let file1 = OS.Path.join(dir, "file1");
+  let file2 = OS.Path.join(dir, "file2");
+  let subDir = OS.Path.join(dir, "subdir");
+  let fileInSubDir = OS.Path.join(subDir, "file");
+
+  // Sanity checking for the test
+  do_check_false((yield OS.File.exists(dir)));
+
+  // Remove non-existent directory
+  let exception = null;
+  try {
+    yield OS.File.removeDir(dir, {ignoreAbsent: false});
+  } catch (ex) {
+    exception = ex;
+  }
+
+  do_check_true(!!exception);
+  do_check_true(exception instanceof OS.File.Error);
+
+  // Remove non-existent directory with ignoreAbsent
+  yield OS.File.removeDir(dir, {ignoreAbsent: true});
+  yield OS.File.removeDir(dir);
+
+  // Remove file with ignoreAbsent: false
+  yield OS.File.writeAtomic(file, "content", { tmpPath: file + ".tmp" });
+  exception = null;
+  try {
+    yield OS.File.removeDir(file, {ignoreAbsent: false});
+  } catch (ex) {
+    exception = ex;
+  }
+
+  do_check_true(!!exception);
+  do_check_true(exception instanceof OS.File.Error);
+
+  // Remove empty directory
+  yield OS.File.makeDir(dir);
+  yield OS.File.removeDir(dir);
+  do_check_false((yield OS.File.exists(dir)));
+
+  // Remove directory that contains one file
+  yield OS.File.makeDir(dir);
+  yield OS.File.writeAtomic(file1, "content", { tmpPath: file1 + ".tmp" });
+  yield OS.File.removeDir(dir);
+  do_check_false((yield OS.File.exists(dir)));
+
+  // Remove directory that contains multiple files
+  yield OS.File.makeDir(dir);
+  yield OS.File.writeAtomic(file1, "content", { tmpPath: file1 + ".tmp" });
+  yield OS.File.writeAtomic(file2, "content", { tmpPath: file2 + ".tmp" });
+  yield OS.File.removeDir(dir);
+  do_check_false((yield OS.File.exists(dir)));
+
+  // Remove directory that contains a file and a directory
+  yield OS.File.makeDir(dir);
+  yield OS.File.writeAtomic(file1, "content", { tmpPath: file1 + ".tmp" });
+  yield OS.File.makeDir(subDir);
+  yield OS.File.writeAtomic(fileInSubDir, "content", { tmpPath: fileInSubDir + ".tmp" });
+  yield OS.File.removeDir(dir);
+  do_check_false((yield OS.File.exists(dir)));
+});
+
+add_task(function* test_unix_symlink() {
+  // Windows does not implement OS.File.unixSymLink()
+  if (OS.Constants.Win) {
+    return;
+  }
+
+  // Android / B2G file systems typically don't support symlinks.
+  if (OS.Constants.Sys.Name == "Android") {
+    return;
+  }
+
+  let file = OS.Path.join(OS.Constants.Path.profileDir, "file");
+  let dir = OS.Path.join(OS.Constants.Path.profileDir, "directory");
+  let file1 = OS.Path.join(dir, "file1");
+
+  // This test will create the following directory structure:
+  // <profileDir>/file                             (regular file)
+  // <profileDir>/file.link => file                (symlink)
+  // <profileDir>/directory                        (directory)
+  // <profileDir>/linkdir => directory             (directory)
+  // <profileDir>/directory/file1                  (regular file)
+  // <profileDir>/directory3                       (directory)
+  // <profileDir>/directory3/file3                 (directory)
+  // <profileDir>/directory/link2 => ../directory3 (regular file)
+
+  // Sanity checking for the test
+  do_check_false((yield OS.File.exists(dir)));
+
+  yield OS.File.writeAtomic(file, "content", { tmpPath: file + ".tmp" });
+  do_check_true((yield OS.File.exists(file)));
+  let info = yield OS.File.stat(file, {unixNoFollowingLinks: true});
+  do_check_false(info.isDir);
+  do_check_false(info.isSymLink);
+
+  yield OS.File.unixSymLink(file, file + ".link");
+  do_check_true((yield OS.File.exists(file + ".link")));
+  info = yield OS.File.stat(file + ".link", {unixNoFollowingLinks: true});
+  do_check_false(info.isDir);
+  do_check_true(info.isSymLink);
+  info = yield OS.File.stat(file + ".link");
+  do_check_false(info.isDir);
+  do_check_false(info.isSymLink);
+  yield OS.File.remove(file + ".link");
+  do_check_false((yield OS.File.exists(file + ".link")));
+
+  yield OS.File.makeDir(dir);
+  do_check_true((yield OS.File.exists(dir)));
+  info = yield OS.File.stat(dir, {unixNoFollowingLinks: true});
+  do_check_true(info.isDir);
+  do_check_false(info.isSymLink);
+
+  let link = OS.Path.join(OS.Constants.Path.profileDir, "linkdir");
+
+  yield OS.File.unixSymLink(dir, link);
+  do_check_true((yield OS.File.exists(link)));
+  info = yield OS.File.stat(link, {unixNoFollowingLinks: true});
+  do_check_false(info.isDir);
+  do_check_true(info.isSymLink);
+  info = yield OS.File.stat(link);
+  do_check_true(info.isDir);
+  do_check_false(info.isSymLink);
+
+  let dir3 = OS.Path.join(OS.Constants.Path.profileDir, "directory3");
+  let file3 = OS.Path.join(dir3, "file3");
+  let link2 = OS.Path.join(dir, "link2");
+
+  yield OS.File.writeAtomic(file1, "content", { tmpPath: file1 + ".tmp" });
+  do_check_true((yield OS.File.exists(file1)));
+  yield OS.File.makeDir(dir3);
+  do_check_true((yield OS.File.exists(dir3)));
+  yield OS.File.writeAtomic(file3, "content", { tmpPath: file3 + ".tmp" });
+  do_check_true((yield OS.File.exists(file3)));
+  yield OS.File.unixSymLink("../directory3", link2);
+  do_check_true((yield OS.File.exists(link2)));
+
+  yield OS.File.removeDir(link);
+  do_check_false((yield OS.File.exists(link)));
+  do_check_true((yield OS.File.exists(file1)));
+  yield OS.File.removeDir(dir);
+  do_check_false((yield OS.File.exists(dir)));
+  do_check_true((yield OS.File.exists(file3)));
+  yield OS.File.removeDir(dir3);
+  do_check_false((yield OS.File.exists(dir3)));
+
+  // This task will be executed only on Unix-like systems.
+  // Please do not add tests independent to operating systems here
+  // or implement symlink() on Windows.
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_removeEmptyDir.js b/toolkit/components/osfile/tests/xpcshell/test_removeEmptyDir.js
new file mode 100644
index 000000000..95f8d5cd1
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_removeEmptyDir.js
@@ -0,0 +1,55 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+do_register_cleanup(function() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", false);
+});
+
+function run_test() {
+  Services.prefs.setBoolPref("toolkit.osfile.log", true);
+
+  run_next_test();
+}
+
+/**
+ * Test OS.File.removeEmptyDir
+ */
+add_task(function() {
+  // Set up profile. We create the directory in the profile, because the profile
+  // is removed after every test run.
+  do_get_profile();
+
+  let dir = OS.Path.join(OS.Constants.Path.profileDir, "directory");
+
+  // Sanity checking for the test
+  do_check_false((yield OS.File.exists(dir)));
+
+  // Remove non-existent directory
+  yield OS.File.removeEmptyDir(dir);
+
+  // Remove non-existent directory with ignoreAbsent
+  yield OS.File.removeEmptyDir(dir, {ignoreAbsent: true});
+
+  // Remove non-existent directory with ignoreAbsent false
+  let exception = null;
+  try {
+    yield OS.File.removeEmptyDir(dir, {ignoreAbsent: false});
+  } catch (ex) {
+    exception = ex;
+  }
+
+  do_check_true(!!exception);
+  do_check_true(exception instanceof OS.File.Error);
+  do_check_true(exception.becauseNoSuchFile);
+
+  // Remove empty directory
+  yield OS.File.makeDir(dir);
+  yield OS.File.removeEmptyDir(dir);
+  do_check_false((yield OS.File.exists(dir)));
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/test_reset.js b/toolkit/components/osfile/tests/xpcshell/test_reset.js
new file mode 100644
index 000000000..f1e1b14d1
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_reset.js
@@ -0,0 +1,95 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+var Path = OS.Constants.Path;
+
+add_task(function* init() {
+  do_get_profile();
+});
+
+add_task(function* reset_before_launching() {
+  do_print("Reset without launching OS.File, it shouldn't break");
+  yield OS.File.resetWorker();
+});
+
+add_task(function* transparent_reset() {
+  for (let i = 1; i < 3; ++i) {
+    do_print("Do stome stuff before and after " + i + " reset(s), " +
+             "it shouldn't break");
+    let CONTENT = "some content " + i;
+    let path = OS.Path.join(Path.profileDir, "tmp");
+    yield OS.File.writeAtomic(path, CONTENT);
+    for (let j = 0; j < i; ++j) {
+      yield OS.File.resetWorker();
+    }
+    let data = yield OS.File.read(path);
+    let string = (new TextDecoder()).decode(data);
+    do_check_eq(string, CONTENT);
+  }
+});
+
+add_task(function* file_open_cannot_reset() {
+  let TEST_FILE = OS.Path.join(Path.profileDir, "tmp-" + Math.random());
+  do_print("Leaking file descriptor " + TEST_FILE + ", we shouldn't be able to reset");
+  let openedFile = yield OS.File.open(TEST_FILE, { create: true} );
+  let thrown = false;
+  try {
+    yield OS.File.resetWorker();
+  } catch (ex if ex.message.indexOf(OS.Path.basename(TEST_FILE)) != -1 ) {
+    thrown = true;
+  }
+  do_check_true(thrown);
+
+  do_print("Closing the file, we should now be able to reset");
+  yield openedFile.close();
+  yield OS.File.resetWorker();
+});
+
+add_task(function* dir_open_cannot_reset() {
+  let TEST_DIR = yield OS.File.getCurrentDirectory();
+  do_print("Leaking directory " + TEST_DIR + ", we shouldn't be able to reset");
+  let iterator = new OS.File.DirectoryIterator(TEST_DIR);
+  let thrown = false;
+  try {
+    yield OS.File.resetWorker();
+  } catch (ex if ex.message.indexOf(OS.Path.basename(TEST_DIR)) != -1 ) {
+    thrown = true;
+  }
+  do_check_true(thrown);
+
+  do_print("Closing the directory, we should now be able to reset");
+  yield iterator.close();
+  yield OS.File.resetWorker();
+});
+
+add_task(function* race_against_itself() {
+  do_print("Attempt to get resetWorker() to race against itself");
+  // Arbitrary operation, just to wake up the worker
+  try {
+    yield OS.File.read("/foo");
+  } catch (ex) {
+  }
+
+  let all = [];
+  for (let i = 0; i < 100; ++i) {
+    all.push(OS.File.resetWorker());
+  }
+
+  yield Promise.all(all);
+});
+
+
+add_task(function* finish_with_a_reset() {
+  do_print("Reset without waiting for the result");
+  // Arbitrary operation, just to wake up the worker
+  try {
+    yield OS.File.read("/foo");
+  } catch (ex) {
+  }
+  // Now reset
+  /*don't yield*/ OS.File.resetWorker();
+});
+
+function run_test() {
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_shutdown.js b/toolkit/components/osfile/tests/xpcshell/test_shutdown.js
new file mode 100644
index 000000000..667965d9e
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_shutdown.js
@@ -0,0 +1,98 @@
+Components.utils.import("resource://gre/modules/Services.jsm", this);
+Components.utils.import("resource://gre/modules/Promise.jsm", this);
+Components.utils.import("resource://gre/modules/Task.jsm", this);
+Components.utils.import("resource://gre/modules/osfile.jsm", this);
+
+add_task(function init() {
+  do_get_profile();
+});
+
+/**
+ * Test logging of file descriptors leaks.
+ */
+add_task(function system_shutdown() {
+
+  // Test that unclosed files cause warnings
+  // Test that unclosed directories cause warnings
+  // Test that closed files do not cause warnings
+  // Test that closed directories do not cause warnings
+  function testLeaksOf(resource, topic) {
+    return Task.spawn(function() {
+      let deferred = Promise.defer();
+
+      // Register observer
+      Services.prefs.setBoolPref("toolkit.asyncshutdown.testing", true);
+      Services.prefs.setBoolPref("toolkit.osfile.log", true);
+      Services.prefs.setBoolPref("toolkit.osfile.log.redirect", true);
+      Services.prefs.setCharPref("toolkit.osfile.test.shutdown.observer", topic);
+
+      let observer = function(aMessage) {
+        try {
+          do_print("Got message: " + aMessage);
+          if (!(aMessage instanceof Components.interfaces.nsIConsoleMessage)) {
+            return;
+          }
+          let message = aMessage.message;
+          do_print("Got message: " + message);
+          if (message.indexOf("TEST OS Controller WARNING") < 0) {
+            return;
+          }
+          do_print("Got message: " + message + ", looking for resource " + resource);
+          if (message.indexOf(resource) < 0) {
+            return;
+          }
+          do_print("Resource: " + resource + " found");
+          do_execute_soon(deferred.resolve);
+        } catch (ex) {
+          do_execute_soon(function() {
+            deferred.reject(ex);
+          });
+        }
+      };
+      Services.console.registerListener(observer);
+      Services.obs.notifyObservers(null, topic, null);
+      do_timeout(1000, function() {
+        do_print("Timeout while waiting for resource: " + resource);
+        deferred.reject("timeout");
+      });
+
+      let resolved = false;
+      try {
+        yield deferred.promise;
+        resolved = true;
+      } catch (ex if ex == "timeout") {
+        resolved = false;
+      }
+      Services.console.unregisterListener(observer);
+      Services.prefs.clearUserPref("toolkit.osfile.log");
+      Services.prefs.clearUserPref("toolkit.osfile.log.redirect");
+      Services.prefs.clearUserPref("toolkit.osfile.test.shutdown.observer");
+      Services.prefs.clearUserPref("toolkit.async_shutdown.testing", true);
+
+      throw new Task.Result(resolved);
+    });
+  }
+
+  let TEST_DIR = OS.Path.join((yield OS.File.getCurrentDirectory()), "..");
+  do_print("Testing for leaks of directory iterator " + TEST_DIR);
+  let iterator = new OS.File.DirectoryIterator(TEST_DIR);
+  do_print("At this stage, we leak the directory");
+  do_check_true((yield testLeaksOf(TEST_DIR, "test.shutdown.dir.leak")));
+  yield iterator.close();
+  do_print("At this stage, we don't leak the directory anymore");
+  do_check_false((yield testLeaksOf(TEST_DIR, "test.shutdown.dir.noleak")));
+
+  let TEST_FILE = OS.Path.join(OS.Constants.Path.profileDir, "test");
+  do_print("Testing for leaks of file descriptor: " + TEST_FILE);
+  let openedFile = yield OS.File.open(TEST_FILE, { create: true} );
+  do_print("At this stage, we leak the file");
+  do_check_true((yield testLeaksOf(TEST_FILE, "test.shutdown.file.leak")));
+  yield openedFile.close();
+  do_print("At this stage, we don't leak the file anymore");
+  do_check_false((yield testLeaksOf(TEST_FILE, "test.shutdown.file.leak.2")));
+});
+
+
+function run_test() {
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_telemetry.js b/toolkit/components/osfile/tests/xpcshell/test_telemetry.js
new file mode 100644
index 000000000..dc5104443
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_telemetry.js
@@ -0,0 +1,63 @@
+"use strict";
+
+var {OS: {File, Path, Constants}} = Components.utils.import("resource://gre/modules/osfile.jsm", {});
+var {Services} = Components.utils.import("resource://gre/modules/Services.jsm", {});
+
+// Ensure that we have a profile but that the OS.File worker is not launched
+add_task(function* init() {
+  do_get_profile();
+  yield File.resetWorker();
+});
+
+function getCount(histogram) {
+  if (histogram == null) {
+    return 0;
+  }
+
+  let total = 0;
+  for (let i of histogram.counts) {
+    total += i;
+  }
+  return total;
+}
+
+// Ensure that launching the OS.File worker adds data to the relevant
+// histograms
+add_task(function* test_startup() {
+  let LAUNCH = "OSFILE_WORKER_LAUNCH_MS";
+  let READY = "OSFILE_WORKER_READY_MS";
+
+  let before = Services.telemetry.histogramSnapshots;
+
+  // Launch the OS.File worker
+  yield File.getCurrentDirectory();
+
+  let after = Services.telemetry.histogramSnapshots;
+
+
+  do_print("Ensuring that we have recorded measures for histograms");
+  do_check_eq(getCount(after[LAUNCH]), getCount(before[LAUNCH]) + 1);
+  do_check_eq(getCount(after[READY]), getCount(before[READY]) + 1);
+
+  do_print("Ensuring that launh <= ready");
+  do_check_true(after[LAUNCH].sum <= after[READY].sum);
+});
+
+// Ensure that calling writeAtomic adds data to the relevant histograms
+add_task(function* test_writeAtomic() {
+  let LABEL = "OSFILE_WRITEATOMIC_JANK_MS";
+
+  let before = Services.telemetry.histogramSnapshots;
+
+  // Perform a write.
+  let path = Path.join(Constants.Path.profileDir, "test_osfile_telemetry.tmp");
+  yield File.writeAtomic(path, LABEL, { tmpPath: path + ".tmp" } );
+
+  let after = Services.telemetry.histogramSnapshots;
+
+  do_check_eq(getCount(after[LABEL]), getCount(before[LABEL]) + 1);
+});
+
+function run_test() {
+  run_next_test();
+}
diff --git a/toolkit/components/osfile/tests/xpcshell/test_unique.js b/toolkit/components/osfile/tests/xpcshell/test_unique.js
new file mode 100644
index 000000000..8aa81b803
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_unique.js
@@ -0,0 +1,88 @@
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+Components.utils.import("resource://gre/modules/Task.jsm");
+
+function run_test() {
+  do_get_profile();
+  run_next_test();
+}
+
+function testFiles(filename) {
+  return Task.spawn(function() {
+    const MAX_TRIES = 10;
+    let profileDir = OS.Constants.Path.profileDir;
+    let path = OS.Path.join(profileDir, filename);
+
+    // Ensure that openUnique() uses the file name if there is no file with that name already.
+    let openedFile = yield OS.File.openUnique(path);
+    do_print("\nCreate new file: " + openedFile.path);
+    yield openedFile.file.close();
+    let exists = yield OS.File.exists(openedFile.path);
+    do_check_true(exists);
+    do_check_eq(path, openedFile.path);
+    let fileInfo = yield OS.File.stat(openedFile.path);
+    do_check_true(fileInfo.size == 0);
+
+    // Ensure that openUnique() creates a new file name using a HEX number, as the original name is already taken.
+    openedFile = yield OS.File.openUnique(path);
+    do_print("\nCreate unique HEX file: " + openedFile.path);
+    yield openedFile.file.close();
+    exists = yield OS.File.exists(openedFile.path);
+    do_check_true(exists);
+    fileInfo = yield OS.File.stat(openedFile.path);
+    do_check_true(fileInfo.size == 0);
+
+    // Ensure that openUnique() generates different file names each time, using the HEX number algorithm
+    let filenames = new Set();
+    for (let i=0; i < MAX_TRIES; i++) {
+      openedFile = yield OS.File.openUnique(path);
+      yield openedFile.file.close();
+      filenames.add(openedFile.path);
+    }
+
+    do_check_eq(filenames.size, MAX_TRIES);
+
+    // Ensure that openUnique() creates a new human readable file name using, as the original name is already taken.
+    openedFile = yield OS.File.openUnique(path, {humanReadable : true});
+    do_print("\nCreate unique Human Readable file: " + openedFile.path);
+    yield openedFile.file.close();
+    exists = yield OS.File.exists(openedFile.path);
+    do_check_true(exists);
+    fileInfo = yield OS.File.stat(openedFile.path);
+    do_check_true(fileInfo.size == 0);
+
+    // Ensure that openUnique() generates different human readable file names each time
+    filenames = new Set();
+    for (let i=0; i < MAX_TRIES; i++) {
+      openedFile = yield OS.File.openUnique(path, {humanReadable : true});
+      yield openedFile.file.close();
+      filenames.add(openedFile.path);
+    }
+
+    do_check_eq(filenames.size, MAX_TRIES);
+
+    let exn;
+    try {
+      for (let i=0; i < 100; i++) {
+        openedFile = yield OS.File.openUnique(path, {humanReadable : true});
+        yield openedFile.file.close();
+      }
+    } catch (ex) {
+      exn = ex;
+    }
+
+    do_print("Ensure that this raises the correct error");
+    do_check_true(!!exn);
+    do_check_true(exn instanceof OS.File.Error);
+    do_check_true(exn.becauseExists);
+  });
+}
+
+add_task(function test_unique() {
+  OS.Shared.DEBUG = true;
+  // Tests files with extension
+  yield testFiles("dummy_unique_file.txt");
+  // Tests files with no extension
+  yield testFiles("dummy_unique_file_no_ext");
+});
diff --git a/toolkit/components/osfile/tests/xpcshell/xpcshell.ini b/toolkit/components/osfile/tests/xpcshell/xpcshell.ini
new file mode 100644
index 000000000..58b106d3d
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/xpcshell.ini
@@ -0,0 +1,51 @@
+[DEFAULT]
+head = head.js
+tail =
+
+support-files =
+  test_loader/module_test_loader.js
+
+[test_available_free_space.js]
+[test_compression.js]
+[test_constants.js]
+[test_creationDate.js]
+[test_duration.js]
+[test_exception.js]
+[test_file_URL_conversion.js]
+[test_loader.js]
+[test_logging.js]
+[test_makeDir.js]
+[test_open.js]
+[test_osfile_async.js]
+[test_osfile_async_append.js]
+[test_osfile_async_bytes.js]
+[test_osfile_async_copy.js]
+[test_osfile_async_flush.js]
+[test_osfile_async_largefiles.js]
+[test_osfile_async_setDates.js]
+# Unimplemented on Windows (bug 1022816).
+# Spurious failure on Android test farm due to non-POSIX behavior of
+# filesystem backing /mnt/sdcard (not worth trying to fix).
+[test_osfile_async_setPermissions.js]
+skip-if = os == "win" || os == "android"
+[test_osfile_closed.js]
+[test_osfile_error.js]
+[test_osfile_kill.js]
+# Windows test
+[test_osfile_win_async_setPermissions.js]
+skip-if = os != "win"
+[test_osfile_writeAtomic_backupTo_option.js]
+[test_osfile_writeAtomic_zerobytes.js]
+[test_path.js]
+[test_path_constants.js]
+[test_queue.js]
+[test_read_write.js]
+requesttimeoutfactor = 4
+[test_remove.js]
+[test_removeDir.js]
+requesttimeoutfactor = 4
+[test_removeEmptyDir.js]
+[test_reset.js]
+[test_shutdown.js]
+[test_telemetry.js]
+[test_unique.js]