Add m-esr52 at 52.6.0

1 files changed, 1663 insertions, 0 deletions

diff --git a/testing/xpcshell/head.js b/testing/xpcshell/head.js
new file mode 100644
index 000000000..74fd482cf
--- /dev/null
+++ b/testing/xpcshell/head.js
@@ -0,0 +1,1663 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* 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/. */
+
+/*
+ * This file contains common code that is loaded before each test file(s).
+ * See http://developer.mozilla.org/en/docs/Writing_xpcshell-based_unit_tests
+ * for more information.
+ */
+
+var _quit = false;
+var _passed = true;
+var _tests_pending = 0;
+var _cleanupFunctions = [];
+var _pendingTimers = [];
+var _profileInitialized = false;
+
+// Register the testing-common resource protocol early, to have access to its
+// modules.
+_register_modules_protocol_handler();
+
+var _Promise = Components.utils.import("resource://gre/modules/Promise.jsm", {}).Promise;
+var _PromiseTestUtils = Components.utils.import("resource://testing-common/PromiseTestUtils.jsm", {}).PromiseTestUtils;
+Components.utils.importGlobalProperties(["XMLHttpRequest"]);
+
+// Support a common assertion library, Assert.jsm.
+var AssertCls = Components.utils.import("resource://testing-common/Assert.jsm", null).Assert;
+// Pass a custom report function for xpcshell-test style reporting.
+var Assert = new AssertCls(function(err, message, stack) {
+  if (err) {
+    do_report_result(false, err.message, err.stack);
+  } else {
+    do_report_result(true, message, stack);
+  }
+});
+
+
+var _add_params = function (params) {
+  if (typeof _XPCSHELL_PROCESS != "undefined") {
+    params.xpcshell_process = _XPCSHELL_PROCESS;
+  }
+};
+
+var _dumpLog = function (raw_msg) {
+  dump("\n" + JSON.stringify(raw_msg) + "\n");
+}
+
+var _LoggerClass = Components.utils.import("resource://testing-common/StructuredLog.jsm", null).StructuredLogger;
+var _testLogger = new _LoggerClass("xpcshell/head.js", _dumpLog, [_add_params]);
+
+// Disable automatic network detection, so tests work correctly when
+// not connected to a network.
+{
+  let ios = Components.classes["@mozilla.org/network/io-service;1"]
+                      .getService(Components.interfaces.nsIIOService2);
+  ios.manageOfflineStatus = false;
+  ios.offline = false;
+}
+
+// Determine if we're running on parent or child
+var runningInParent = true;
+try {
+  runningInParent = Components.classes["@mozilla.org/xre/runtime;1"].
+                    getService(Components.interfaces.nsIXULRuntime).processType
+                    == Components.interfaces.nsIXULRuntime.PROCESS_TYPE_DEFAULT;
+}
+catch (e) { }
+
+// Only if building of places is enabled.
+if (runningInParent &&
+    "mozIAsyncHistory" in Components.interfaces) {
+  // Ensure places history is enabled for xpcshell-tests as some non-FF
+  // apps disable it.
+  let prefs = Components.classes["@mozilla.org/preferences-service;1"]
+              .getService(Components.interfaces.nsIPrefBranch);
+  prefs.setBoolPref("places.history.enabled", true);
+}
+
+try {
+  if (runningInParent) {
+    let prefs = Components.classes["@mozilla.org/preferences-service;1"]
+                .getService(Components.interfaces.nsIPrefBranch);
+
+    // disable necko IPC security checks for xpcshell, as they lack the
+    // docshells needed to pass them
+    prefs.setBoolPref("network.disable.ipc.security", true);
+
+    // Disable IPv6 lookups for 'localhost' on windows.
+    if ("@mozilla.org/windows-registry-key;1" in Components.classes) {
+      prefs.setCharPref("network.dns.ipv4OnlyDomains", "localhost");
+    }
+  }
+}
+catch (e) { }
+
+// Configure crash reporting, if possible
+// We rely on the Python harness to set MOZ_CRASHREPORTER,
+// MOZ_CRASHREPORTER_NO_REPORT, and handle checking for minidumps.
+// Note that if we're in a child process, we don't want to init the
+// crashreporter component.
+try {
+  if (runningInParent &&
+      "@mozilla.org/toolkit/crash-reporter;1" in Components.classes) {
+    let crashReporter =
+          Components.classes["@mozilla.org/toolkit/crash-reporter;1"]
+          .getService(Components.interfaces.nsICrashReporter);
+    crashReporter.UpdateCrashEventsDir();
+    crashReporter.minidumpPath = do_get_minidumpdir();
+  }
+}
+catch (e) { }
+
+// Configure a console listener so messages sent to it are logged as part
+// of the test.
+try {
+  let levelNames = {}
+  for (let level of ["debug", "info", "warn", "error"]) {
+    levelNames[Components.interfaces.nsIConsoleMessage[level]] = level;
+  }
+
+  let listener = {
+    QueryInterface : function(iid) {
+      if (!iid.equals(Components.interfaces.nsISupports) &&
+          !iid.equals(Components.interfaces.nsIConsoleListener)) {
+        throw Components.results.NS_NOINTERFACE;
+      }
+      return this;
+    },
+    observe : function (msg) {
+      if (typeof do_print === "function")
+        do_print("CONSOLE_MESSAGE: (" + levelNames[msg.logLevel] + ") " + msg.toString());
+    }
+  };
+  Components.classes["@mozilla.org/consoleservice;1"]
+            .getService(Components.interfaces.nsIConsoleService)
+            .registerListener(listener);
+} catch (e) {}
+/**
+ * Date.now() is not necessarily monotonically increasing (insert sob story
+ * about times not being the right tool to use for measuring intervals of time,
+ * robarnold can tell all), so be wary of error by erring by at least
+ * _timerFuzz ms.
+ */
+const _timerFuzz = 15;
+
+function _Timer(func, delay) {
+  delay = Number(delay);
+  if (delay < 0)
+    do_throw("do_timeout() delay must be nonnegative");
+
+  if (typeof func !== "function")
+    do_throw("string callbacks no longer accepted; use a function!");
+
+  this._func = func;
+  this._start = Date.now();
+  this._delay = delay;
+
+  var timer = Components.classes["@mozilla.org/timer;1"]
+                        .createInstance(Components.interfaces.nsITimer);
+  timer.initWithCallback(this, delay + _timerFuzz, timer.TYPE_ONE_SHOT);
+
+  // Keep timer alive until it fires
+  _pendingTimers.push(timer);
+}
+_Timer.prototype = {
+  QueryInterface: function(iid) {
+    if (iid.equals(Components.interfaces.nsITimerCallback) ||
+        iid.equals(Components.interfaces.nsISupports))
+      return this;
+
+    throw Components.results.NS_ERROR_NO_INTERFACE;
+  },
+
+  notify: function(timer) {
+    _pendingTimers.splice(_pendingTimers.indexOf(timer), 1);
+
+    // The current nsITimer implementation can undershoot, but even if it
+    // couldn't, paranoia is probably a virtue here given the potential for
+    // random orange on tinderboxen.
+    var end = Date.now();
+    var elapsed = end - this._start;
+    if (elapsed >= this._delay) {
+      try {
+        this._func.call(null);
+      } catch (e) {
+        do_throw("exception thrown from do_timeout callback: " + e);
+      }
+      return;
+    }
+
+    // Timer undershot, retry with a little overshoot to try to avoid more
+    // undershoots.
+    var newDelay = this._delay - elapsed;
+    do_timeout(newDelay, this._func);
+  }
+};
+
+function _do_main() {
+  if (_quit)
+    return;
+
+  _testLogger.info("running event loop");
+
+  var thr = Components.classes["@mozilla.org/thread-manager;1"]
+                      .getService().currentThread;
+
+  while (!_quit)
+    thr.processNextEvent(true);
+
+  while (thr.hasPendingEvents())
+    thr.processNextEvent(true);
+}
+
+function _do_quit() {
+  _testLogger.info("exiting test");
+  _quit = true;
+}
+
+/**
+ * Overrides idleService with a mock.  Idle is commonly used for maintenance
+ * tasks, thus if a test uses a service that requires the idle service, it will
+ * start handling them.
+ * This behaviour would cause random failures and slowdown tests execution,
+ * for example by running database vacuum or cleanups for each test.
+ *
+ * @note Idle service is overridden by default.  If a test requires it, it will
+ *       have to call do_get_idle() function at least once before use.
+ */
+var _fakeIdleService = {
+  get registrar() {
+    delete this.registrar;
+    return this.registrar =
+      Components.manager.QueryInterface(Components.interfaces.nsIComponentRegistrar);
+  },
+  contractID: "@mozilla.org/widget/idleservice;1",
+  get CID() {
+    return this.registrar.contractIDToCID(this.contractID);
+  },
+
+  activate: function FIS_activate()
+  {
+    if (!this.originalFactory) {
+      // Save original factory.
+      this.originalFactory =
+        Components.manager.getClassObject(Components.classes[this.contractID],
+                                          Components.interfaces.nsIFactory);
+      // Unregister original factory.
+      this.registrar.unregisterFactory(this.CID, this.originalFactory);
+      // Replace with the mock.
+      this.registrar.registerFactory(this.CID, "Fake Idle Service",
+                                     this.contractID, this.factory
+      );
+    }
+  },
+
+  deactivate: function FIS_deactivate()
+  {
+    if (this.originalFactory) {
+      // Unregister the mock.
+      this.registrar.unregisterFactory(this.CID, this.factory);
+      // Restore original factory.
+      this.registrar.registerFactory(this.CID, "Idle Service",
+                                     this.contractID, this.originalFactory);
+      delete this.originalFactory;
+    }
+  },
+
+  factory: {
+    // nsIFactory
+    createInstance: function (aOuter, aIID)
+    {
+      if (aOuter) {
+        throw Components.results.NS_ERROR_NO_AGGREGATION;
+      }
+      return _fakeIdleService.QueryInterface(aIID);
+    },
+    lockFactory: function (aLock) {
+      throw Components.results.NS_ERROR_NOT_IMPLEMENTED;
+    },
+    QueryInterface: function(aIID) {
+      if (aIID.equals(Components.interfaces.nsIFactory) ||
+          aIID.equals(Components.interfaces.nsISupports)) {
+        return this;
+      }
+      throw Components.results.NS_ERROR_NO_INTERFACE;
+    }
+  },
+
+  // nsIIdleService
+  get idleTime() {
+    return 0;
+  },
+  addIdleObserver: function () {},
+  removeIdleObserver: function () {},
+
+  QueryInterface: function(aIID) {
+    // Useful for testing purposes, see test_get_idle.js.
+    if (aIID.equals(Components.interfaces.nsIFactory)) {
+      return this.factory;
+    }
+    if (aIID.equals(Components.interfaces.nsIIdleService) ||
+        aIID.equals(Components.interfaces.nsISupports)) {
+      return this;
+    }
+    throw Components.results.NS_ERROR_NO_INTERFACE;
+  }
+}
+
+/**
+ * Restores the idle service factory if needed and returns the service's handle.
+ * @return A handle to the idle service.
+ */
+function do_get_idle() {
+  _fakeIdleService.deactivate();
+  return Components.classes[_fakeIdleService.contractID]
+                   .getService(Components.interfaces.nsIIdleService);
+}
+
+// Map resource://test/ to current working directory and
+// resource://testing-common/ to the shared test modules directory.
+function _register_protocol_handlers() {
+  let ios = Components.classes["@mozilla.org/network/io-service;1"]
+                      .getService(Components.interfaces.nsIIOService);
+  let protocolHandler =
+    ios.getProtocolHandler("resource")
+       .QueryInterface(Components.interfaces.nsIResProtocolHandler);
+
+  let curDirURI = ios.newFileURI(do_get_cwd());
+  protocolHandler.setSubstitution("test", curDirURI);
+
+  _register_modules_protocol_handler();
+}
+
+function _register_modules_protocol_handler() {
+  if (!_TESTING_MODULES_DIR) {
+    throw new Error("Please define a path where the testing modules can be " +
+                    "found in a variable called '_TESTING_MODULES_DIR' before " +
+                    "head.js is included.");
+  }
+
+  let ios = Components.classes["@mozilla.org/network/io-service;1"]
+                      .getService(Components.interfaces.nsIIOService);
+  let protocolHandler =
+    ios.getProtocolHandler("resource")
+       .QueryInterface(Components.interfaces.nsIResProtocolHandler);
+
+  let modulesFile = Components.classes["@mozilla.org/file/local;1"].
+                    createInstance(Components.interfaces.nsILocalFile);
+  modulesFile.initWithPath(_TESTING_MODULES_DIR);
+
+  if (!modulesFile.exists()) {
+    throw new Error("Specified modules directory does not exist: " +
+                    _TESTING_MODULES_DIR);
+  }
+
+  if (!modulesFile.isDirectory()) {
+    throw new Error("Specified modules directory is not a directory: " +
+                    _TESTING_MODULES_DIR);
+  }
+
+  let modulesURI = ios.newFileURI(modulesFile);
+
+  protocolHandler.setSubstitution("testing-common", modulesURI);
+}
+
+/* Debugging support */
+// Used locally and by our self-tests.
+function _setupDebuggerServer(breakpointFiles, callback) {
+  let prefs = Components.classes["@mozilla.org/preferences-service;1"]
+              .getService(Components.interfaces.nsIPrefBranch);
+
+  // Always allow remote debugging.
+  prefs.setBoolPref("devtools.debugger.remote-enabled", true);
+
+  // for debugging-the-debugging, let an env var cause log spew.
+  let env = Components.classes["@mozilla.org/process/environment;1"]
+                      .getService(Components.interfaces.nsIEnvironment);
+  if (env.get("DEVTOOLS_DEBUGGER_LOG")) {
+    prefs.setBoolPref("devtools.debugger.log", true);
+  }
+  if (env.get("DEVTOOLS_DEBUGGER_LOG_VERBOSE")) {
+    prefs.setBoolPref("devtools.debugger.log.verbose", true);
+  }
+
+  let require;
+  try {
+    ({ require } = Components.utils.import("resource://devtools/shared/Loader.jsm", {}));
+  } catch (e) {
+    throw new Error("resource://devtools appears to be inaccessible from the " +
+                    "xpcshell environment.\n" +
+                    "This can usually be resolved by adding:\n" +
+                    "  firefox-appdir = browser\n" +
+                    "to the xpcshell.ini manifest.\n" +
+                    "It is possible for this to alter test behevior by " +
+                    "triggering additional browser code to run, so check " +
+                    "test behavior after making this change.\n" +
+                    "See also https://bugzil.la/1215378.")
+  }
+  let { DebuggerServer } = require("devtools/server/main");
+  let { OriginalLocation } = require("devtools/server/actors/common");
+  DebuggerServer.init();
+  DebuggerServer.addBrowserActors();
+  DebuggerServer.addActors("resource://testing-common/dbg-actors.js");
+  DebuggerServer.allowChromeProcess = true;
+
+  // An observer notification that tells us when we can "resume" script
+  // execution.
+  let obsSvc = Components.classes["@mozilla.org/observer-service;1"].
+               getService(Components.interfaces.nsIObserverService);
+
+  const TOPICS = ["devtools-thread-resumed", "xpcshell-test-devtools-shutdown"];
+  let observe = function(subject, topic, data) {
+    switch (topic) {
+      case "devtools-thread-resumed":
+        // Exceptions in here aren't reported and block the debugger from
+        // resuming, so...
+        try {
+          // Add a breakpoint for the first line in our test files.
+          let threadActor = subject.wrappedJSObject;
+          for (let file of breakpointFiles) {
+            // Pass an empty `source` object to workaround `source` function assertion
+            let sourceActor = threadActor.sources.source({originalUrl: file, source: {}});
+            sourceActor._getOrCreateBreakpointActor(new OriginalLocation(sourceActor, 1));
+          }
+        } catch (ex) {
+          do_print("Failed to initialize breakpoints: " + ex + "\n" + ex.stack);
+        }
+        break;
+      case "xpcshell-test-devtools-shutdown":
+        // the debugger has shutdown before we got a resume event - nothing
+        // special to do here.
+        break;
+    }
+    for (let topicToRemove of TOPICS) {
+      obsSvc.removeObserver(observe, topicToRemove);
+    }
+    callback();
+  };
+
+  for (let topic of TOPICS) {
+    obsSvc.addObserver(observe, topic, false);
+  }
+  return DebuggerServer;
+}
+
+function _initDebugging(port) {
+  let initialized = false;
+  let DebuggerServer = _setupDebuggerServer(_TEST_FILE, () => {initialized = true;});
+
+  do_print("");
+  do_print("*******************************************************************");
+  do_print("Waiting for the debugger to connect on port " + port)
+  do_print("")
+  do_print("To connect the debugger, open a Firefox instance, select 'Connect'");
+  do_print("from the Developer menu and specify the port as " + port);
+  do_print("*******************************************************************");
+  do_print("")
+
+  let AuthenticatorType = DebuggerServer.Authenticators.get("PROMPT");
+  let authenticator = new AuthenticatorType.Server();
+  authenticator.allowConnection = () => {
+    return DebuggerServer.AuthenticationResult.ALLOW;
+  };
+
+  let listener = DebuggerServer.createListener();
+  listener.portOrPath = port;
+  listener.authenticator = authenticator;
+  listener.open();
+
+  // spin an event loop until the debugger connects.
+  let thr = Components.classes["@mozilla.org/thread-manager;1"]
+              .getService().currentThread;
+  while (!initialized) {
+    do_print("Still waiting for debugger to connect...");
+    thr.processNextEvent(true);
+  }
+  // NOTE: if you want to debug the harness itself, you can now add a 'debugger'
+  // statement anywhere and it will stop - but we've already added a breakpoint
+  // for the first line of the test scripts, so we just continue...
+  do_print("Debugger connected, starting test execution");
+}
+
+function _execute_test() {
+  // _JSDEBUGGER_PORT is dynamically defined by <runxpcshelltests.py>.
+  if (_JSDEBUGGER_PORT) {
+    try {
+      _initDebugging(_JSDEBUGGER_PORT);
+    } catch (ex) {
+      // Fail the test run immediately if debugging is requested but fails, so
+      // that the failure state is more obvious.
+      do_throw(`Failed to initialize debugging: ${ex}`, ex.stack);
+    }
+  }
+
+  _register_protocol_handlers();
+
+  // Override idle service by default.
+  // Call do_get_idle() to restore the factory and get the service.
+  _fakeIdleService.activate();
+
+  _PromiseTestUtils.init();
+  _PromiseTestUtils.Assert = Assert;
+
+  let coverageCollector = null;
+  if (typeof _JSCOV_DIR === 'string') {
+    let _CoverageCollector = Components.utils.import("resource://testing-common/CoverageUtils.jsm", {}).CoverageCollector;
+    coverageCollector = new _CoverageCollector(_JSCOV_DIR);
+  }
+
+  // _HEAD_FILES is dynamically defined by <runxpcshelltests.py>.
+  _load_files(_HEAD_FILES);
+  // _TEST_FILE is dynamically defined by <runxpcshelltests.py>.
+  _load_files(_TEST_FILE);
+
+  // Tack Assert.jsm methods to the current scope.
+  this.Assert = Assert;
+  for (let func in Assert) {
+    this[func] = Assert[func].bind(Assert);
+  }
+
+  if (_gTestHasOnly) {
+    _gTests = _gTests.filter(([props,]) => {
+      return ("_only" in props) && props._only;
+    });
+  }
+
+  try {
+    do_test_pending("MAIN run_test");
+    // Check if run_test() is defined. If defined, run it.
+    // Else, call run_next_test() directly to invoke tests
+    // added by add_test() and add_task().
+    if (typeof run_test === "function") {
+      run_test();
+    } else {
+      run_next_test();
+    }
+
+    if (coverageCollector != null) {
+      coverageCollector.recordTestCoverage(_TEST_FILE[0]);
+    }
+
+    do_test_finished("MAIN run_test");
+    _do_main();
+    _PromiseTestUtils.assertNoUncaughtRejections();
+  } catch (e) {
+    _passed = false;
+    // do_check failures are already logged and set _quit to true and throw
+    // NS_ERROR_ABORT. If both of those are true it is likely this exception
+    // has already been logged so there is no need to log it again. It's
+    // possible that this will mask an NS_ERROR_ABORT that happens after a
+    // do_check failure though.
+    if (coverageCollector != null) {
+      coverageCollector.recordTestCoverage(_TEST_FILE[0]);
+    }
+
+    if (!_quit || e != Components.results.NS_ERROR_ABORT) {
+      let extra = {};
+      if (e.fileName) {
+        extra.source_file = e.fileName;
+        if (e.lineNumber) {
+          extra.line_number = e.lineNumber;
+        }
+      } else {
+        extra.source_file = "xpcshell/head.js";
+      }
+      let message = _exception_message(e);
+      if (e.stack) {
+        extra.stack = _format_stack(e.stack);
+      }
+      _testLogger.error(message, extra);
+    }
+  }
+
+  if (coverageCollector != null) {
+    coverageCollector.finalize();
+  }
+
+  // _TAIL_FILES is dynamically defined by <runxpcshelltests.py>.
+  _load_files(_TAIL_FILES);
+
+  // Execute all of our cleanup functions.
+  let reportCleanupError = function(ex) {
+    let stack, filename;
+    if (ex && typeof ex == "object" && "stack" in ex) {
+      stack = ex.stack;
+    } else {
+      stack = Components.stack.caller;
+    }
+    if (stack instanceof Components.interfaces.nsIStackFrame) {
+      filename = stack.filename;
+    } else if (ex.fileName) {
+      filename = ex.fileName;
+    }
+    _testLogger.error(_exception_message(ex),
+                      {
+                        stack: _format_stack(stack),
+                        source_file: filename
+                      });
+  };
+
+  let func;
+  while ((func = _cleanupFunctions.pop())) {
+    let result;
+    try {
+      result = func();
+    } catch (ex) {
+      reportCleanupError(ex);
+      continue;
+    }
+    if (result && typeof result == "object"
+        && "then" in result && typeof result.then == "function") {
+      // This is a promise, wait until it is satisfied before proceeding
+      let complete = false;
+      let promise = result.then(null, reportCleanupError);
+      promise = promise.then(() => complete = true);
+      let thr = Components.classes["@mozilla.org/thread-manager;1"]
+                  .getService().currentThread;
+      while (!complete) {
+        thr.processNextEvent(true);
+      }
+    }
+  }
+
+  // Restore idle service to avoid leaks.
+  _fakeIdleService.deactivate();
+
+  if (_profileInitialized) {
+    // Since we have a profile, we will notify profile shutdown topics at
+    // the end of the current test, to ensure correct cleanup on shutdown.
+    let obs = Components.classes["@mozilla.org/observer-service;1"]
+                        .getService(Components.interfaces.nsIObserverService);
+    obs.notifyObservers(null, "profile-change-net-teardown", null);
+    obs.notifyObservers(null, "profile-change-teardown", null);
+    obs.notifyObservers(null, "profile-before-change", null);
+    obs.notifyObservers(null, "profile-before-change-qm", null);
+
+    _profileInitialized = false;
+  }
+
+  try {
+    _PromiseTestUtils.ensureDOMPromiseRejectionsProcessed();
+    _PromiseTestUtils.assertNoUncaughtRejections();
+    _PromiseTestUtils.assertNoMoreExpectedRejections();
+  } finally {
+    // It's important to terminate the module to avoid crashes on shutdown.
+    _PromiseTestUtils.uninit();
+  }
+}
+
+/**
+ * Loads files.
+ *
+ * @param aFiles Array of files to load.
+ */
+function _load_files(aFiles) {
+  function load_file(element, index, array) {
+    try {
+      load(element);
+    } catch (e) {
+      let extra = {
+        source_file: element
+      }
+      if (e.stack) {
+        extra.stack = _format_stack(e.stack);
+      }
+      _testLogger.error(_exception_message(e), extra);
+    }
+  }
+
+  aFiles.forEach(load_file);
+}
+
+function _wrap_with_quotes_if_necessary(val) {
+  return typeof val == "string" ? '"' + val + '"' : val;
+}
+
+/************** Functions to be used from the tests **************/
+
+/**
+ * Prints a message to the output log.
+ */
+function do_print(msg, data) {
+  msg = _wrap_with_quotes_if_necessary(msg);
+  data = data ? data : null;
+  _testLogger.info(msg, data);
+}
+
+/**
+ * Calls the given function at least the specified number of milliseconds later.
+ * The callback will not undershoot the given time, but it might overshoot --
+ * don't expect precision!
+ *
+ * @param delay : uint
+ *   the number of milliseconds to delay
+ * @param callback : function() : void
+ *   the function to call
+ */
+function do_timeout(delay, func) {
+  new _Timer(func, Number(delay));
+}
+
+function do_execute_soon(callback, aName) {
+  let funcName = (aName ? aName : callback.name);
+  do_test_pending(funcName);
+  var tm = Components.classes["@mozilla.org/thread-manager;1"]
+                     .getService(Components.interfaces.nsIThreadManager);
+
+  tm.mainThread.dispatch({
+    run: function() {
+      try {
+        callback();
+      } catch (e) {
+        // do_check failures are already logged and set _quit to true and throw
+        // NS_ERROR_ABORT. If both of those are true it is likely this exception
+        // has already been logged so there is no need to log it again. It's
+        // possible that this will mask an NS_ERROR_ABORT that happens after a
+        // do_check failure though.
+        if (!_quit || e != Components.results.NS_ERROR_ABORT) {
+          let stack = e.stack ? _format_stack(e.stack) : null;
+          _testLogger.testStatus(_TEST_NAME,
+                                 funcName,
+                                 'FAIL',
+                                 'PASS',
+                                 _exception_message(e),
+                                 stack);
+          _do_quit();
+        }
+      }
+      finally {
+        do_test_finished(funcName);
+      }
+    }
+  }, Components.interfaces.nsIThread.DISPATCH_NORMAL);
+}
+
+/**
+ * Shows an error message and the current stack and aborts the test.
+ *
+ * @param error  A message string or an Error object.
+ * @param stack  null or nsIStackFrame object or a string containing
+ *               \n separated stack lines (as in Error().stack).
+ */
+function do_throw(error, stack) {
+  let filename = "";
+  // If we didn't get passed a stack, maybe the error has one
+  // otherwise get it from our call context
+  stack = stack || error.stack || Components.stack.caller;
+
+  if (stack instanceof Components.interfaces.nsIStackFrame)
+    filename = stack.filename;
+  else if (error.fileName)
+    filename = error.fileName;
+
+  _testLogger.error(_exception_message(error),
+                    {
+                      source_file: filename,
+                      stack: _format_stack(stack)
+                    });
+  _abort_failed_test();
+}
+
+function _abort_failed_test() {
+  // Called to abort the test run after all failures are logged.
+  _passed = false;
+  _do_quit();
+  throw Components.results.NS_ERROR_ABORT;
+}
+
+function _format_stack(stack) {
+  let normalized;
+  if (stack instanceof Components.interfaces.nsIStackFrame) {
+    let frames = [];
+    for (let frame = stack; frame; frame = frame.caller) {
+      frames.push(frame.filename + ":" + frame.name + ":" + frame.lineNumber);
+    }
+    normalized = frames.join("\n");
+  } else {
+    normalized = "" + stack;
+  }
+  return _Task.Debugging.generateReadableStack(normalized, "    ");
+}
+
+// Make a nice display string from an object that behaves
+// like Error
+function _exception_message(ex) {
+  let message = "";
+  if (ex.name) {
+    message = ex.name + ": ";
+  }
+  if (ex.message) {
+    message += ex.message;
+  }
+  if (ex.fileName) {
+    message += (" at " + ex.fileName);
+    if (ex.lineNumber) {
+      message += (":" + ex.lineNumber);
+    }
+  }
+  if (message !== "") {
+    return message;
+  }
+  // Force ex to be stringified
+  return "" + ex;
+}
+
+function do_report_unexpected_exception(ex, text) {
+  let filename = Components.stack.caller.filename;
+  text = text ? text + " - " : "";
+
+  _passed = false;
+  _testLogger.error(text + "Unexpected exception " + _exception_message(ex),
+                    {
+                      source_file: filename,
+                      stack: _format_stack(ex.stack)
+                    });
+  _do_quit();
+  throw Components.results.NS_ERROR_ABORT;
+}
+
+function do_note_exception(ex, text) {
+  let filename = Components.stack.caller.filename;
+  _testLogger.info(text + "Swallowed exception " + _exception_message(ex),
+                   {
+                     source_file: filename,
+                     stack: _format_stack(ex.stack)
+                   });
+}
+
+function _do_check_neq(left, right, stack, todo) {
+  Assert.notEqual(left, right);
+}
+
+function do_check_neq(left, right, stack) {
+  if (!stack)
+    stack = Components.stack.caller;
+
+  _do_check_neq(left, right, stack, false);
+}
+
+function todo_check_neq(left, right, stack) {
+  if (!stack)
+      stack = Components.stack.caller;
+
+  _do_check_neq(left, right, stack, true);
+}
+
+function do_report_result(passed, text, stack, todo) {
+  while (stack.filename.includes("head.js") && stack.caller) {
+    stack = stack.caller;
+  }
+
+  let name = _gRunningTest ? _gRunningTest.name : stack.name;
+  let message;
+  if (name) {
+     message = "[" + name + " : " + stack.lineNumber + "] " + text;
+  } else {
+    message = text;
+  }
+
+  if (passed) {
+    if (todo) {
+      _testLogger.testStatus(_TEST_NAME,
+                             name,
+                             "PASS",
+                             "FAIL",
+                             message,
+                             _format_stack(stack));
+      _abort_failed_test();
+    } else {
+      _testLogger.testStatus(_TEST_NAME,
+                             name,
+                             "PASS",
+                             "PASS",
+                             message);
+    }
+  } else {
+    if (todo) {
+      _testLogger.testStatus(_TEST_NAME,
+                             name,
+                             "FAIL",
+                             "FAIL",
+                             message);
+    } else {
+      _testLogger.testStatus(_TEST_NAME,
+                             name,
+                             "FAIL",
+                             "PASS",
+                             message,
+                             _format_stack(stack));
+      _abort_failed_test();
+    }
+  }
+}
+
+function _do_check_eq(left, right, stack, todo) {
+  if (!stack)
+    stack = Components.stack.caller;
+
+  var text = _wrap_with_quotes_if_necessary(left) + " == " +
+             _wrap_with_quotes_if_necessary(right);
+  do_report_result(left == right, text, stack, todo);
+}
+
+function do_check_eq(left, right, stack) {
+  Assert.equal(left, right);
+}
+
+function todo_check_eq(left, right, stack) {
+  if (!stack)
+      stack = Components.stack.caller;
+
+  _do_check_eq(left, right, stack, true);
+}
+
+function do_check_true(condition, stack) {
+  Assert.ok(condition, stack);
+}
+
+function todo_check_true(condition, stack) {
+  if (!stack)
+    stack = Components.stack.caller;
+
+  todo_check_eq(condition, true, stack);
+}
+
+function do_check_false(condition, stack) {
+  Assert.ok(!condition, stack);
+}
+
+function todo_check_false(condition, stack) {
+  if (!stack)
+    stack = Components.stack.caller;
+
+  todo_check_eq(condition, false, stack);
+}
+
+function do_check_null(condition, stack) {
+  Assert.equal(condition, null);
+}
+
+function todo_check_null(condition, stack=Components.stack.caller) {
+  todo_check_eq(condition, null, stack);
+}
+function do_check_matches(pattern, value) {
+  Assert.deepEqual(pattern, value);
+}
+
+// Check that |func| throws an nsIException that has
+// |Components.results[resultName]| as the value of its 'result' property.
+function do_check_throws_nsIException(func, resultName,
+                                      stack=Components.stack.caller, todo=false)
+{
+  let expected = Components.results[resultName];
+  if (typeof expected !== 'number') {
+    do_throw("do_check_throws_nsIException requires a Components.results" +
+             " property name, not " + uneval(resultName), stack);
+  }
+
+  let msg = ("do_check_throws_nsIException: func should throw" +
+             " an nsIException whose 'result' is Components.results." +
+             resultName);
+
+  try {
+    func();
+  } catch (ex) {
+    if (!(ex instanceof Components.interfaces.nsIException) ||
+        ex.result !== expected) {
+      do_report_result(false, msg + ", threw " + legible_exception(ex) +
+                       " instead", stack, todo);
+    }
+
+    do_report_result(true, msg, stack, todo);
+    return;
+  }
+
+  // Call this here, not in the 'try' clause, so do_report_result's own
+  // throw doesn't get caught by our 'catch' clause.
+  do_report_result(false, msg + ", but returned normally", stack, todo);
+}
+
+// Produce a human-readable form of |exception|. This looks up
+// Components.results values, tries toString methods, and so on.
+function legible_exception(exception)
+{
+  switch (typeof exception) {
+    case 'object':
+    if (exception instanceof Components.interfaces.nsIException) {
+      return "nsIException instance: " + uneval(exception.toString());
+    }
+    return exception.toString();
+
+    case 'number':
+    for (let name in Components.results) {
+      if (exception === Components.results[name]) {
+        return "Components.results." + name;
+      }
+    }
+
+    // Fall through.
+    default:
+    return uneval(exception);
+  }
+}
+
+function do_check_instanceof(value, constructor,
+                             stack=Components.stack.caller, todo=false) {
+  do_report_result(value instanceof constructor,
+                   "value should be an instance of " + constructor.name,
+                   stack, todo);
+}
+
+function todo_check_instanceof(value, constructor,
+                             stack=Components.stack.caller) {
+  do_check_instanceof(value, constructor, stack, true);
+}
+
+function do_test_pending(aName) {
+  ++_tests_pending;
+
+  _testLogger.info("(xpcshell/head.js) | test" +
+                   (aName ? " " + aName : "") +
+                   " pending (" + _tests_pending + ")");
+}
+
+function do_test_finished(aName) {
+  _testLogger.info("(xpcshell/head.js) | test" +
+                   (aName ? " " + aName : "") +
+                   " finished (" + _tests_pending + ")");
+  if (--_tests_pending == 0)
+    _do_quit();
+}
+
+function do_get_file(path, allowNonexistent) {
+  try {
+    let lf = Components.classes["@mozilla.org/file/directory_service;1"]
+      .getService(Components.interfaces.nsIProperties)
+      .get("CurWorkD", Components.interfaces.nsILocalFile);
+
+    let bits = path.split("/");
+    for (let i = 0; i < bits.length; i++) {
+      if (bits[i]) {
+        if (bits[i] == "..")
+          lf = lf.parent;
+        else
+          lf.append(bits[i]);
+      }
+    }
+
+    if (!allowNonexistent && !lf.exists()) {
+      // Not using do_throw(): caller will continue.
+      _passed = false;
+      var stack = Components.stack.caller;
+      _testLogger.error("[" + stack.name + " : " + stack.lineNumber + "] " +
+                        lf.path + " does not exist");
+    }
+
+    return lf;
+  }
+  catch (ex) {
+    do_throw(ex.toString(), Components.stack.caller);
+  }
+
+  return null;
+}
+
+// do_get_cwd() isn't exactly self-explanatory, so provide a helper
+function do_get_cwd() {
+  return do_get_file("");
+}
+
+function do_load_manifest(path) {
+  var lf = do_get_file(path);
+  const nsIComponentRegistrar = Components.interfaces.nsIComponentRegistrar;
+  do_check_true(Components.manager instanceof nsIComponentRegistrar);
+  // Previous do_check_true() is not a test check.
+  Components.manager.autoRegister(lf);
+}
+
+/**
+ * Parse a DOM document.
+ *
+ * @param aPath File path to the document.
+ * @param aType Content type to use in DOMParser.
+ *
+ * @return nsIDOMDocument from the file.
+ */
+function do_parse_document(aPath, aType) {
+  switch (aType) {
+    case "application/xhtml+xml":
+    case "application/xml":
+    case "text/xml":
+      break;
+
+    default:
+      do_throw("type: expected application/xhtml+xml, application/xml or text/xml," +
+                 " got '" + aType + "'",
+               Components.stack.caller);
+  }
+
+  let file = do_get_file(aPath),
+      ios = Components.classes['@mozilla.org/network/io-service;1']
+            .getService(Components.interfaces.nsIIOService),
+      url = ios.newFileURI(file).spec;
+  file = null;
+  return new Promise((resolve, reject) => {
+    let xhr = new XMLHttpRequest();
+    xhr.open("GET", url);
+    xhr.responseType = "document";
+    xhr.onerror = reject;
+    xhr.onload = () => {
+      resolve(xhr.response);
+    };
+    xhr.send();
+  });
+}
+
+/**
+ * Registers a function that will run when the test harness is done running all
+ * tests.
+ *
+ * @param aFunction
+ *        The function to be called when the test harness has finished running.
+ */
+function do_register_cleanup(aFunction)
+{
+  _cleanupFunctions.push(aFunction);
+}
+
+/**
+ * Returns the directory for a temp dir, which is created by the
+ * test harness. Every test gets its own temp dir.
+ *
+ * @return nsILocalFile of the temporary directory
+ */
+function do_get_tempdir() {
+  let env = Components.classes["@mozilla.org/process/environment;1"]
+                      .getService(Components.interfaces.nsIEnvironment);
+  // the python harness sets this in the environment for us
+  let path = env.get("XPCSHELL_TEST_TEMP_DIR");
+  let file = Components.classes["@mozilla.org/file/local;1"]
+                       .createInstance(Components.interfaces.nsILocalFile);
+  file.initWithPath(path);
+  return file;
+}
+
+/**
+ * Returns the directory for crashreporter minidumps.
+ *
+ * @return nsILocalFile of the minidump directory
+ */
+function do_get_minidumpdir() {
+  let env = Components.classes["@mozilla.org/process/environment;1"]
+                      .getService(Components.interfaces.nsIEnvironment);
+  // the python harness may set this in the environment for us
+  let path = env.get("XPCSHELL_MINIDUMP_DIR");
+  if (path) {
+    let file = Components.classes["@mozilla.org/file/local;1"]
+                         .createInstance(Components.interfaces.nsILocalFile);
+    file.initWithPath(path);
+    return file;
+  } else {
+    return do_get_tempdir();
+  }
+}
+
+/**
+ * Registers a directory with the profile service,
+ * and return the directory as an nsILocalFile.
+ *
+ * @param notifyProfileAfterChange Whether to notify for "profile-after-change".
+ * @return nsILocalFile of the profile directory.
+ */
+function do_get_profile(notifyProfileAfterChange = false) {
+  if (!runningInParent) {
+    _testLogger.info("Ignoring profile creation from child process.");
+    return null;
+  }
+
+  let env = Components.classes["@mozilla.org/process/environment;1"]
+                      .getService(Components.interfaces.nsIEnvironment);
+  // the python harness sets this in the environment for us
+  let profd = env.get("XPCSHELL_TEST_PROFILE_DIR");
+  let file = Components.classes["@mozilla.org/file/local;1"]
+                       .createInstance(Components.interfaces.nsILocalFile);
+  file.initWithPath(profd);
+
+  let dirSvc = Components.classes["@mozilla.org/file/directory_service;1"]
+                         .getService(Components.interfaces.nsIProperties);
+  let provider = {
+    getFile: function(prop, persistent) {
+      persistent.value = true;
+      if (prop == "ProfD" || prop == "ProfLD" || prop == "ProfDS" ||
+          prop == "ProfLDS" || prop == "TmpD") {
+        return file.clone();
+      }
+      return null;
+    },
+    QueryInterface: function(iid) {
+      if (iid.equals(Components.interfaces.nsIDirectoryServiceProvider) ||
+          iid.equals(Components.interfaces.nsISupports)) {
+        return this;
+      }
+      throw Components.results.NS_ERROR_NO_INTERFACE;
+    }
+  };
+  dirSvc.QueryInterface(Components.interfaces.nsIDirectoryService)
+        .registerProvider(provider);
+
+  let obsSvc = Components.classes["@mozilla.org/observer-service;1"].
+        getService(Components.interfaces.nsIObserverService);
+
+  // We need to update the crash events directory when the profile changes.
+  if (runningInParent &&
+      "@mozilla.org/toolkit/crash-reporter;1" in Components.classes) {
+    let crashReporter =
+        Components.classes["@mozilla.org/toolkit/crash-reporter;1"]
+                          .getService(Components.interfaces.nsICrashReporter);
+    crashReporter.UpdateCrashEventsDir();
+  }
+
+  if (!_profileInitialized) {
+    obsSvc.notifyObservers(null, "profile-do-change", "xpcshell-do-get-profile");
+    _profileInitialized = true;
+    if (notifyProfileAfterChange) {
+      obsSvc.notifyObservers(null, "profile-after-change", "xpcshell-do-get-profile");
+    }
+  }
+
+  // The methods of 'provider' will retain this scope so null out everything
+  // to avoid spurious leak reports.
+  env = null;
+  profd = null;
+  dirSvc = null;
+  provider = null;
+  obsSvc = null;
+  return file.clone();
+}
+
+/**
+ * This function loads head.js (this file) in the child process, so that all
+ * functions defined in this file (do_throw, etc) are available to subsequent
+ * sendCommand calls.  It also sets various constants used by these functions.
+ *
+ * (Note that you may use sendCommand without calling this function first;  you
+ * simply won't have any of the functions in this file available.)
+ */
+function do_load_child_test_harness()
+{
+  // Make sure this isn't called from child process
+  if (!runningInParent) {
+    do_throw("run_test_in_child cannot be called from child!");
+  }
+
+  // Allow to be called multiple times, but only run once
+  if (typeof do_load_child_test_harness.alreadyRun != "undefined")
+    return;
+  do_load_child_test_harness.alreadyRun = 1;
+
+  _XPCSHELL_PROCESS = "parent";
+
+  let command =
+        "const _HEAD_JS_PATH=" + uneval(_HEAD_JS_PATH) + "; "
+      + "const _HEAD_FILES=" + uneval(_HEAD_FILES) + "; "
+      + "const _MOZINFO_JS_PATH=" + uneval(_MOZINFO_JS_PATH) + "; "
+      + "const _TAIL_FILES=" + uneval(_TAIL_FILES) + "; "
+      + "const _TEST_NAME=" + uneval(_TEST_NAME) + "; "
+      // We'll need more magic to get the debugger working in the child
+      + "const _JSDEBUGGER_PORT=0; "
+      + "const _XPCSHELL_PROCESS='child';";
+
+  if (typeof _JSCOV_DIR === 'string') {
+    command += " const _JSCOV_DIR=" + uneval(_JSCOV_DIR) + ";";
+  }
+
+  if (_TESTING_MODULES_DIR) {
+    command += " const _TESTING_MODULES_DIR=" + uneval(_TESTING_MODULES_DIR) + ";";
+  }
+
+  command += " load(_HEAD_JS_PATH);";
+  sendCommand(command);
+}
+
+/**
+ * Runs an entire xpcshell unit test in a child process (rather than in chrome,
+ * which is the default).
+ *
+ * This function returns immediately, before the test has completed.
+ *
+ * @param testFile
+ *        The name of the script to run.  Path format same as load().
+ * @param optionalCallback.
+ *        Optional function to be called (in parent) when test on child is
+ *        complete.  If provided, the function must call do_test_finished();
+ * @return Promise Resolved when the test in the child is complete.
+ */
+function run_test_in_child(testFile, optionalCallback)
+{
+  return new Promise((resolve) => {
+    var callback = () => {
+      resolve();
+      if (typeof optionalCallback == 'undefined') {
+        do_test_finished();
+      } else {
+        optionalCallback();
+      }
+    };
+
+    do_load_child_test_harness();
+
+    var testPath = do_get_file(testFile).path.replace(/\\/g, "/");
+    do_test_pending("run in child");
+    sendCommand("_testLogger.info('CHILD-TEST-STARTED'); "
+                + "const _TEST_FILE=['" + testPath + "']; "
+                + "_execute_test(); "
+                + "_testLogger.info('CHILD-TEST-COMPLETED');",
+                callback);
+  });
+}
+
+/**
+ * Execute a given function as soon as a particular cross-process message is received.
+ * Must be paired with do_send_remote_message or equivalent ProcessMessageManager calls.
+ *
+ * @param optionalCallback
+ *        Optional callback that is invoked when the message is received.  If provided,
+ *        the function must call do_test_finished().
+ * @return Promise Promise that is resolved when the message is received.
+ */
+function do_await_remote_message(name, optionalCallback)
+{
+  return new Promise((resolve) => {
+    var listener = {
+      receiveMessage: function(message) {
+        if (message.name == name) {
+          mm.removeMessageListener(name, listener);
+          resolve();
+          if (optionalCallback) {
+            optionalCallback();
+          } else {
+            do_test_finished();
+          }
+        }
+      }
+    };
+
+    var mm;
+    if (runningInParent) {
+      mm = Cc["@mozilla.org/parentprocessmessagemanager;1"].getService(Ci.nsIMessageBroadcaster);
+    } else {
+      mm = Cc["@mozilla.org/childprocessmessagemanager;1"].getService(Ci.nsISyncMessageSender);
+    }
+    do_test_pending();
+    mm.addMessageListener(name, listener);
+  });
+}
+
+/**
+ * Asynchronously send a message to all remote processes. Pairs with do_await_remote_message
+ * or equivalent ProcessMessageManager listeners.
+ */
+function do_send_remote_message(name) {
+  var mm;
+  var sender;
+  if (runningInParent) {
+    mm = Cc["@mozilla.org/parentprocessmessagemanager;1"].getService(Ci.nsIMessageBroadcaster);
+    sender = 'broadcastAsyncMessage';
+  } else {
+    mm = Cc["@mozilla.org/childprocessmessagemanager;1"].getService(Ci.nsISyncMessageSender);
+    sender = 'sendAsyncMessage';
+  }
+  mm[sender](name);
+}
+
+/**
+ * Helper function to add the _only property to add_task/add_test function when
+ * running it as add_task.only(...).
+ *
+ * @param addFunc
+ *        The parent function to call, e.g. add_task or add_test.
+ * @param funcOrProperties
+ *        A function to be run or an object represents test properties.
+ * @param func
+ *        A function to be run only if the funcOrProperies is not a function.
+ */
+function _add_only(addFunc, funcOrProperties, func) {
+  _gTestHasOnly = true;
+  if (typeof funcOrProperties == "function") {
+    func = funcOrProperties;
+    funcOrProperties = {};
+  }
+
+  if (typeof funcOrProperties == "object") {
+    funcOrProperties._only = true;
+  }
+  return addFunc(funcOrProperties, func);
+}
+
+/**
+ * Helper function to skip the test using e.g. add_task.skip(...)
+ *
+ * @param addFunc
+ *        The parent function to call, e.g. add_task or add_test.
+ * @param funcOrProperties
+ *        A function to be run or an object represents test properties.
+ * @param func
+ *        A function to be run only if the funcOrProperies is not a function.
+ */
+function _add_skip(addFunc, funcOrProperties, func) {
+  if (typeof funcOrProperties == "function") {
+    func = funcOrProperties;
+    funcOrProperties = {};
+  }
+
+  if (typeof funcOrProperties == "object") {
+    funcOrProperties.skip_if = () => true;
+  }
+  return addFunc(funcOrProperties, func);
+}
+
+/**
+ * Add a test function to the list of tests that are to be run asynchronously.
+ *
+ * @param funcOrProperties
+ *        A function to be run or an object represents test properties.
+ *        Supported properties:
+ *          skip_if : An arrow function which has an expression to be
+ *                    evaluated whether the test is skipped or not.
+ * @param func
+ *        A function to be run only if the funcOrProperies is not a function.
+ *
+ * Each test function must call run_next_test() when it's done. Test files
+ * should call run_next_test() in their run_test function to execute all
+ * async tests.
+ *
+ * @return the test function that was passed in.
+ */
+var _gTests = [];
+function add_test(funcOrProperties, func) {
+  if (typeof funcOrProperties == "function") {
+    _gTests.push([{ _isTask: false }, funcOrProperties]);
+  } else if (typeof funcOrProperties == "object") {
+    funcOrProperties._isTask = false;
+    _gTests.push([funcOrProperties, func]);
+  } else {
+    do_throw("add_test() should take a function or an object and a function");
+  }
+  return func;
+}
+add_test.only = _add_only.bind(undefined, add_test);
+add_test.skip = _add_skip.bind(undefined, add_test);
+
+/**
+ * Add a test function which is a Task function.
+ *
+ * @param funcOrProperties
+ *        A generator function to be run or an object represents test
+ *        properties.
+ *        Supported properties:
+ *          skip_if : An arrow function which has an expression to be
+ *                    evaluated whether the test is skipped or not.
+ * @param func
+ *        A generator function to be run only if the funcOrProperies is not a
+ *        function.
+ *
+ * Task functions are functions fed into Task.jsm's Task.spawn(). They are
+ * generators that emit promises.
+ *
+ * If an exception is thrown, a do_check_* comparison fails, or if a rejected
+ * promise is yielded, the test function aborts immediately and the test is
+ * reported as a failure.
+ *
+ * Unlike add_test(), there is no need to call run_next_test(). The next test
+ * will run automatically as soon the task function is exhausted. To trigger
+ * premature (but successful) termination of the function, simply return or
+ * throw a Task.Result instance.
+ *
+ * Example usage:
+ *
+ * add_task(function* test() {
+ *   let result = yield Promise.resolve(true);
+ *
+ *   do_check_true(result);
+ *
+ *   let secondary = yield someFunctionThatReturnsAPromise(result);
+ *   do_check_eq(secondary, "expected value");
+ * });
+ *
+ * add_task(function* test_early_return() {
+ *   let result = yield somethingThatReturnsAPromise();
+ *
+ *   if (!result) {
+ *     // Test is ended immediately, with success.
+ *     return;
+ *   }
+ *
+ *   do_check_eq(result, "foo");
+ * });
+ *
+ * add_task({
+ *   skip_if: () => !("@mozilla.org/telephony/volume-service;1" in Components.classes),
+ * }, function* test_volume_service() {
+ *   let volumeService = Cc["@mozilla.org/telephony/volume-service;1"]
+ *     .getService(Ci.nsIVolumeService);
+ *   ...
+ * });
+ */
+function add_task(funcOrProperties, func) {
+  if (typeof funcOrProperties == "function") {
+    _gTests.push([{ _isTask: true }, funcOrProperties]);
+  } else if (typeof funcOrProperties == "object") {
+    funcOrProperties._isTask = true;
+    _gTests.push([funcOrProperties, func]);
+  } else {
+    do_throw("add_task() should take a function or an object and a function");
+  }
+}
+add_task.only = _add_only.bind(undefined, add_task);
+add_task.skip = _add_skip.bind(undefined, add_task);
+
+var _Task = Components.utils.import("resource://gre/modules/Task.jsm", {}).Task;
+_Task.Debugging.maintainStack = true;
+
+
+/**
+ * Runs the next test function from the list of async tests.
+ */
+var _gRunningTest = null;
+var _gTestIndex = 0; // The index of the currently running test.
+var _gTaskRunning = false;
+var _gTestHasOnly = false;
+function run_next_test()
+{
+  if (_gTaskRunning) {
+    throw new Error("run_next_test() called from an add_task() test function. " +
+                    "run_next_test() should not be called from inside add_task() " +
+                    "under any circumstances!");
+  }
+
+  function _run_next_test()
+  {
+    if (_gTestIndex < _gTests.length) {
+      // Check for uncaught rejections as early and often as possible.
+      _PromiseTestUtils.assertNoUncaughtRejections();
+      let _properties;
+      [_properties, _gRunningTest,] = _gTests[_gTestIndex++];
+      if (typeof(_properties.skip_if) == "function" && _properties.skip_if()) {
+        let _condition = _properties.skip_if.toSource().replace(/\(\)\s*=>\s*/, "");
+        let _message = _gRunningTest.name
+          + " skipped because the following conditions were"
+          + " met: (" + _condition + ")";
+        _testLogger.testStatus(_TEST_NAME,
+                               _gRunningTest.name,
+                               "SKIP",
+                               "SKIP",
+                               _message);
+        do_execute_soon(run_next_test);
+        return;
+      }
+      _testLogger.info(_TEST_NAME + " | Starting " + _gRunningTest.name);
+      do_test_pending(_gRunningTest.name);
+
+      if (_properties._isTask) {
+        _gTaskRunning = true;
+        _Task.spawn(_gRunningTest).then(() => {
+          _gTaskRunning = false;
+          run_next_test();
+        }, ex => {
+          _gTaskRunning = false;
+          try {
+            do_report_unexpected_exception(ex);
+          } catch (ex) {
+            // The above throws NS_ERROR_ABORT and we don't want this to show up
+            // as an unhandled rejection later.
+          }
+        });
+      } else {
+        // Exceptions do not kill asynchronous tests, so they'll time out.
+        try {
+          _gRunningTest();
+        } catch (e) {
+          do_throw(e);
+        }
+      }
+    }
+  }
+
+  // For sane stacks during failures, we execute this code soon, but not now.
+  // We do this now, before we call do_test_finished(), to ensure the pending
+  // counter (_tests_pending) never reaches 0 while we still have tests to run
+  // (do_execute_soon bumps that counter).
+  do_execute_soon(_run_next_test, "run_next_test " + _gTestIndex);
+
+  if (_gRunningTest !== null) {
+    // Close the previous test do_test_pending call.
+    do_test_finished(_gRunningTest.name);
+  }
+}
+
+try {
+  if (runningInParent) {
+    // Always use network provider for geolocation tests
+    // so we bypass the OSX dialog raised by the corelocation provider
+    let prefs = Components.classes["@mozilla.org/preferences-service;1"]
+      .getService(Components.interfaces.nsIPrefBranch);
+
+    prefs.setBoolPref("geo.provider.testing", true);
+  }
+} catch (e) { }
+
+// We need to avoid hitting the network with certain components.
+try {
+  if (runningInParent) {
+    let prefs = Components.classes["@mozilla.org/preferences-service;1"]
+      .getService(Components.interfaces.nsIPrefBranch);
+
+    prefs.setCharPref("media.gmp-manager.url.override", "http://%(server)s/dummy-gmp-manager.xml");
+    prefs.setCharPref("media.gmp-manager.updateEnabled", false);
+    prefs.setCharPref("extensions.systemAddon.update.url", "http://%(server)s/dummy-system-addons.xml");
+    prefs.setCharPref("browser.selfsupport.url", "https://%(server)s/selfsupport-dummy/");
+    prefs.setCharPref("toolkit.telemetry.server", "https://%(server)s/telemetry-dummy");
+    prefs.setCharPref("browser.search.geoip.url", "https://%(server)s/geoip-dummy");
+  }
+} catch (e) { }
+
+// Make tests run consistently on DevEdition (which has a lightweight theme
+// selected by default).
+try {
+  if (runningInParent) {
+    let prefs = Components.classes["@mozilla.org/preferences-service;1"]
+      .getService(Components.interfaces.nsIPrefBranch);
+
+    prefs.deleteBranch("lightweightThemes.selectedThemeID");
+    prefs.deleteBranch("browser.devedition.theme.enabled");
+  }
+} catch (e) { }
+
+function _load_mozinfo() {
+  let mozinfoFile = Components.classes["@mozilla.org/file/local;1"]
+    .createInstance(Components.interfaces.nsIFile);
+  mozinfoFile.initWithPath(_MOZINFO_JS_PATH);
+  let stream = Components.classes["@mozilla.org/network/file-input-stream;1"]
+    .createInstance(Components.interfaces.nsIFileInputStream);
+  stream.init(mozinfoFile, -1, 0, 0);
+  let json = Components.classes["@mozilla.org/dom/json;1"]
+    .createInstance(Components.interfaces.nsIJSON);
+  let mozinfo = json.decodeFromStream(stream, stream.available());
+  stream.close();
+  return mozinfo;
+}
+
+Object.defineProperty(this, "mozinfo", {
+  configurable: true,
+  get() {
+    let _mozinfo = _load_mozinfo();
+    Object.defineProperty(this, "mozinfo", {
+      configurable: false,
+      value: _mozinfo
+    });
+    return _mozinfo;
+  }
+});