Add m-esr52 at 52.6.0

1 files changed, 657 insertions, 0 deletions

diff --git a/addon-sdk/source/test/test-loader.js b/addon-sdk/source/test/test-loader.js
new file mode 100644
index 000000000..3ee3e34f0
--- /dev/null
+++ b/addon-sdk/source/test/test-loader.js
@@ -0,0 +1,657 @@
+/* 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';
+
+var {
+  Loader, main, unload, parseStack, resolve, join,
+  Require, Module
+} = require('toolkit/loader');
+var { readURI } = require('sdk/net/url');
+
+var root = module.uri.substr(0, module.uri.lastIndexOf('/'));
+
+const app = require('sdk/system/xul-app');
+
+// The following adds Debugger constructor to the global namespace.
+const { Cu } = require('chrome');
+const { addDebuggerToGlobal } = Cu.import('resource://gre/modules/jsdebugger.jsm', {});
+addDebuggerToGlobal(this);
+
+exports['test resolve'] = function (assert) {
+  let cuddlefish_id = 'sdk/loader/cuddlefish';
+  assert.equal(resolve('../index.js', './dir/c.js'), './index.js');
+  assert.equal(resolve('./index.js', './dir/c.js'), './dir/index.js');
+  assert.equal(resolve('./dir/c.js', './index.js'), './dir/c.js');
+  assert.equal(resolve('../utils/file.js', './dir/b.js'), './utils/file.js');
+
+  assert.equal(resolve('../utils/./file.js', './dir/b.js'), './utils/file.js');
+  assert.equal(resolve('../utils/file.js', './'), './../utils/file.js');
+  assert.equal(resolve('./utils/file.js', './'), './utils/file.js');
+  assert.equal(resolve('./utils/file.js', './index.js'), './utils/file.js');
+
+  assert.equal(resolve('../utils/./file.js', cuddlefish_id), 'sdk/utils/file.js');
+  assert.equal(resolve('../utils/file.js', cuddlefish_id), 'sdk/utils/file.js');
+  assert.equal(resolve('./utils/file.js', cuddlefish_id), 'sdk/loader/utils/file.js');
+
+  assert.equal(resolve('..//index.js', './dir/c.js'), './index.js');
+  assert.equal(resolve('../modules/XPCOMUtils.jsm', 'resource://gre/utils/file.js'), 'resource://gre/modules/XPCOMUtils.jsm');
+  assert.equal(resolve('../modules/XPCOMUtils.jsm', 'chrome://gre/utils/file.js'), 'chrome://gre/modules/XPCOMUtils.jsm');
+  assert.equal(resolve('../../a/b/c.json', 'file:///thing/utils/file.js'), 'file:///a/b/c.json');
+
+  // Does not change absolute paths
+  assert.equal(resolve('resource://gre/modules/file.js', './dir/b.js'),
+    'resource://gre/modules/file.js');
+  assert.equal(resolve('file:///gre/modules/file.js', './dir/b.js'),
+    'file:///gre/modules/file.js');
+  assert.equal(resolve('/root.js', './dir/b.js'),
+    '/root.js');
+};
+
+exports['test join'] = function (assert) {
+  assert.equal(join('a/path', '../../../module'), '../module');
+  assert.equal(join('a/path/to', '../module'), 'a/path/module');
+  assert.equal(join('a/path/to', './module'), 'a/path/to/module');
+  assert.equal(join('a/path/to', '././../module'), 'a/path/module');
+  assert.equal(join('resource://my/path/yeah/yuh', '../whoa'),
+    'resource://my/path/yeah/whoa');
+  assert.equal(join('resource://my/path/yeah/yuh', './whoa'),
+    'resource://my/path/yeah/yuh/whoa');
+  assert.equal(join('resource:///my/path/yeah/yuh', '../whoa'),
+    'resource:///my/path/yeah/whoa');
+  assert.equal(join('resource:///my/path/yeah/yuh', './whoa'),
+    'resource:///my/path/yeah/yuh/whoa');
+  assert.equal(join('file:///my/path/yeah/yuh', '../whoa'),
+    'file:///my/path/yeah/whoa');
+  assert.equal(join('file:///my/path/yeah/yuh', './whoa'),
+    'file:///my/path/yeah/yuh/whoa');
+  assert.equal(join('a/path/to', '..//module'), 'a/path/module');
+};
+
+exports['test dependency cycles'] = function(assert) {
+  let uri = root + '/fixtures/loader/cycles/';
+  let loader = Loader({ paths: { '': uri } });
+
+  let program = main(loader, 'main');
+
+  assert.equal(program.a.b, program.b, 'module `a` gets correct `b`');
+  assert.equal(program.b.a, program.a, 'module `b` gets correct `a`');
+  assert.equal(program.c.main, program, 'module `c` gets correct `main`');
+
+  unload(loader);
+}
+
+exports['test syntax errors'] = function(assert) {
+  let uri = root + '/fixtures/loader/syntax-error/';
+  let loader = Loader({ paths: { '': uri } });
+
+  try {
+    let program = main(loader, 'main');
+  } catch (error) {
+    assert.equal(error.name, "SyntaxError", "throws syntax error");
+    assert.equal(error.fileName.split("/").pop(), "error.js",
+              "Error contains filename");
+    assert.equal(error.lineNumber, 11, "error is on line 11");
+    let stack = parseStack(error.stack);
+
+    assert.equal(stack.pop().fileName, uri + "error.js",
+                 "last frame file containing syntax error");
+    assert.equal(stack.pop().fileName, uri + "main.js",
+                 "previous frame is a requirer module");
+    assert.equal(stack.pop().fileName, module.uri,
+                 "previous to it is a test module");
+
+  } finally {
+    unload(loader);
+  }
+}
+
+exports['test sandboxes are not added if error'] = function (assert) {
+  let uri = root + '/fixtures/loader/missing-twice/';
+  let loader = Loader({ paths: { '': uri } });
+  let program = main(loader, 'main');
+  assert.ok(!(uri + 'not-found.js' in loader.sandboxes), 'not-found.js not in loader.sandboxes');
+}
+
+exports['test missing module'] = function(assert) {
+  let uri = root + '/fixtures/loader/missing/'
+  let loader = Loader({ paths: { '': uri } });
+
+  try {
+    let program = main(loader, 'main')
+  } catch (error) {
+    assert.equal(error.message, "Module `not-found` is not found at " +
+                uri + "not-found.js", "throws if error not found");
+
+    assert.equal(error.fileName.split("/").pop(), "main.js",
+                 "Error fileName is requirer module");
+
+    assert.equal(error.lineNumber, 7, "error is on line 7");
+
+    let stack = parseStack(error.stack);
+
+    assert.equal(stack.pop().fileName, uri + "main.js",
+                 "loader stack is omitted");
+
+    assert.equal(stack.pop().fileName, module.uri,
+                 "previous in the stack is test module");
+  } finally {
+    unload(loader);
+  }
+}
+
+exports["test invalid module not cached and throws everytime"] = function(assert) {
+  let uri = root + "/fixtures/loader/missing-twice/";
+  let loader = Loader({ paths: { "": uri } });
+
+  let { firstError, secondError, invalidJSON1, invalidJSON2 } = main(loader, "main");
+  assert.equal(firstError.message, "Module `not-found` is not found at " +
+    uri + "not-found.js", "throws on first invalid require");
+  assert.equal(firstError.lineNumber, 8, "first error is on line 7");
+  assert.equal(secondError.message, "Module `not-found` is not found at " +
+    uri + "not-found.js", "throws on second invalid require");
+  assert.equal(secondError.lineNumber, 14, "second error is on line 14");
+
+  assert.equal(invalidJSON1.message,
+    "JSON.parse: unexpected character at line 1 column 1 of the JSON data",
+    "throws on invalid JSON");
+  assert.equal(invalidJSON2.message,
+    "JSON.parse: unexpected character at line 1 column 1 of the JSON data",
+    "throws on invalid JSON second time");
+};
+
+exports['test exceptions in modules'] = function(assert) {
+  let uri = root + '/fixtures/loader/exceptions/'
+
+  let loader = Loader({ paths: { '': uri } });
+
+  try {
+    let program = main(loader, 'main')
+  } catch (error) {
+    assert.equal(error.message, "Boom!", "thrown errors propagate");
+
+    assert.equal(error.fileName.split("/").pop(), "boomer.js",
+                 "Error comes from the module that threw it");
+
+    assert.equal(error.lineNumber, 8, "error is on line 8");
+
+    let stack = parseStack(error.stack);
+
+    let frame = stack.pop()
+    assert.equal(frame.fileName, uri + "boomer.js",
+                 "module that threw is first in the stack");
+    assert.equal(frame.name, "exports.boom",
+                 "name is in the stack");
+
+    frame = stack.pop()
+    assert.equal(frame.fileName, uri + "main.js",
+                 "module that called it is next in the stack");
+    assert.equal(frame.lineNumber, 9, "caller line is in the stack");
+
+
+    assert.equal(stack.pop().fileName, module.uri,
+                 "this test module is next in the stack");
+  } finally {
+    unload(loader);
+  }
+}
+
+exports['test early errors in module'] = function(assert) {
+  let uri = root + '/fixtures/loader/errors/';
+  let loader = Loader({ paths: { '': uri } });
+
+  try {
+    let program = main(loader, 'main')
+  } catch (error) {
+    assert.equal(String(error),
+                 "Error: opening input stream (invalid filename?)",
+                 "thrown errors propagate");
+
+    assert.equal(error.fileName.split("/").pop(), "boomer.js",
+                 "Error comes from the module that threw it");
+
+    assert.equal(error.lineNumber, 7, "error is on line 7");
+
+    let stack = parseStack(error.stack);
+
+    let frame = stack.pop()
+    assert.equal(frame.fileName, uri + "boomer.js",
+                 "module that threw is first in the stack");
+
+    frame = stack.pop()
+    assert.equal(frame.fileName, uri + "main.js",
+                 "module that called it is next in the stack");
+    assert.equal(frame.lineNumber, 7, "caller line is in the stack");
+
+
+    assert.equal(stack.pop().fileName, module.uri,
+                 "this test module is next in the stack");
+  } finally {
+    unload(loader);
+  }
+};
+
+exports['test require json'] = function (assert) {
+  let data = require('./fixtures/loader/json/manifest.json');
+  assert.equal(data.name, 'Jetpack Loader Test', 'loads json with strings');
+  assert.equal(data.version, '1.0.1', 'loads json with strings');
+  assert.equal(data.dependencies.async, '*', 'loads json with objects');
+  assert.equal(data.dependencies.underscore, '*', 'loads json with objects');
+  assert.equal(data.contributors.length, 4, 'loads json with arrays');
+  assert.ok(Array.isArray(data.contributors), 'loads json with arrays');
+  data.version = '2.0.0';
+  let newdata = require('./fixtures/loader/json/manifest.json');
+  assert.equal(newdata.version, '2.0.0',
+    'JSON objects returned should be cached and the same instance');
+
+  try {
+    require('./fixtures/loader/json/invalid.json');
+    assert.fail('Error not thrown when loading invalid json');
+  } catch (err) {
+    assert.ok(err, 'error thrown when loading invalid json');
+    assert.ok(/JSON\.parse/.test(err.message),
+      'should thrown an error from JSON.parse, not attempt to load .json.js');
+  }
+
+  // Try again to ensure an empty module isn't loaded from cache
+  try {
+    require('./fixtures/loader/json/invalid.json');
+    assert.fail('Error not thrown when loading invalid json a second time');
+  } catch (err) {
+    assert.ok(err,
+      'error thrown when loading invalid json a second time');
+    assert.ok(/JSON\.parse/.test(err.message),
+      'should thrown an error from JSON.parse a second time, not attempt to load .json.js');
+  }
+};
+
+exports['test setting metadata for newly created sandboxes'] = function(assert) {
+  let addonID = 'random-addon-id';
+  let uri = root + '/fixtures/loader/cycles/';
+  let loader = Loader({ paths: { '': uri }, id: addonID });
+
+  let dbg = new Debugger();
+  dbg.onNewGlobalObject = function(global) {
+    dbg.onNewGlobalObject = undefined;
+
+    let metadata = Cu.getSandboxMetadata(global.unsafeDereference());
+    assert.ok(metadata, 'this global has attached metadata');
+    assert.equal(metadata.URI, uri + 'main.js', 'URI is set properly');
+    assert.equal(metadata.addonID, addonID, 'addon ID is set');
+  }
+
+  let program = main(loader, 'main');
+};
+
+exports['test require .json, .json.js'] = function (assert) {
+  let testjson = require('./fixtures/loader/json/test.json');
+  assert.equal(testjson.filename, 'test.json',
+    'require("./x.json") should load x.json, not x.json.js');
+
+  let nodotjson = require('./fixtures/loader/json/nodotjson.json');
+  assert.equal(nodotjson.filename, 'nodotjson.json.js',
+    'require("./x.json") should load x.json.js when x.json does not exist');
+  nodotjson.data.prop = 'hydralisk';
+
+  // require('nodotjson.json') and require('nodotjson.json.js')
+  // should resolve to the same file
+  let nodotjsonjs = require('./fixtures/loader/json/nodotjson.json.js');
+  assert.equal(nodotjsonjs.data.prop, 'hydralisk',
+    'js modules are cached whether access via .json.js or .json');
+};
+
+exports['test invisibleToDebugger: false'] = function (assert) {
+  let uri = root + '/fixtures/loader/cycles/';
+  let loader = Loader({ paths: { '': uri } });
+  main(loader, 'main');
+
+  let dbg = new Debugger();
+  let sandbox = loader.sandboxes[uri + 'main.js'];
+
+  try {
+    dbg.addDebuggee(sandbox);
+    assert.ok(true, 'debugger added visible value');
+  } catch(e) {
+    assert.fail('debugger could not add visible value');
+  }
+};
+
+exports['test invisibleToDebugger: true'] = function (assert) {
+  let uri = root + '/fixtures/loader/cycles/';
+  let loader = Loader({ paths: { '': uri }, invisibleToDebugger: true });
+  main(loader, 'main');
+
+  let dbg = new Debugger();
+  let sandbox = loader.sandboxes[uri + 'main.js'];
+
+  try {
+    dbg.addDebuggee(sandbox);
+    assert.fail('debugger added invisible value');
+  } catch(e) {
+    assert.ok(true, 'debugger did not add invisible value');
+  }
+};
+
+exports['test console global by default'] = function (assert) {
+  let uri = root + '/fixtures/loader/globals/';
+  let loader = Loader({ paths: { '': uri }});
+  let program = main(loader, 'main');
+
+  assert.ok(typeof program.console === 'object', 'global `console` exists');
+  assert.ok(typeof program.console.log === 'function', 'global `console.log` exists');
+
+  let loader2 = Loader({ paths: { '': uri }, globals: { console: fakeConsole }});
+  let program2 = main(loader2, 'main');
+
+  assert.equal(program2.console, fakeConsole,
+    'global console can be overridden with Loader options');
+  function fakeConsole () {};
+};
+
+exports['test shared globals'] = function(assert) {
+  let uri = root + '/fixtures/loader/cycles/';
+  let loader = Loader({ paths: { '': uri }, sharedGlobal: true,
+                        sharedGlobalBlocklist: ['b'] });
+
+  let program = main(loader, 'main');
+
+  // As it is hard to verify what is the global of an object
+  // (due to wrappers) we check that we see the `foo` symbol
+  // being manually injected into the shared global object
+  loader.sharedGlobalSandbox.foo = true;
+
+  let m = loader.sandboxes[uri + 'main.js'];
+  let a = loader.sandboxes[uri + 'a.js'];
+  let b = loader.sandboxes[uri + 'b.js'];
+
+  assert.ok(Cu.getGlobalForObject(m).foo, "main is shared");
+  assert.ok(Cu.getGlobalForObject(a).foo, "a is shared");
+  assert.ok(!Cu.getGlobalForObject(b).foo, "b isn't shared");
+
+  unload(loader);
+}
+
+exports['test deprecated shared globals exception name'] = function(assert) {
+  let uri = root + '/fixtures/loader/cycles/';
+  let loader = Loader({ paths: { '': uri }, sharedGlobal: true,
+                        sharedGlobalBlacklist: ['b'] });
+
+  let program = main(loader, 'main');
+
+  assert.ok(loader.sharedGlobalBlocklist.includes("b"), "b should be in the blocklist");
+  assert.equal(loader.sharedGlobalBlocklist.length, loader.sharedGlobalBlacklist.length,
+               "both blocklists should have the same number of items.");
+  assert.equal(loader.sharedGlobalBlocklist.join(","), loader.sharedGlobalBlacklist.join(","),
+               "both blocklists should have the same items.");
+
+  // As it is hard to verify what is the global of an object
+  // (due to wrappers) we check that we see the `foo` symbol
+  // being manually injected into the shared global object
+  loader.sharedGlobalSandbox.foo = true;
+
+  let m = loader.sandboxes[uri + 'main.js'];
+  let a = loader.sandboxes[uri + 'a.js'];
+  let b = loader.sandboxes[uri + 'b.js'];
+
+  assert.ok(Cu.getGlobalForObject(m).foo, "main is shared");
+  assert.ok(Cu.getGlobalForObject(a).foo, "a is shared");
+  assert.ok(!Cu.getGlobalForObject(b).foo, "b isn't shared");
+
+  unload(loader);
+}
+
+exports['test prototype of global'] = function (assert) {
+  let uri = root + '/fixtures/loader/globals/';
+  let loader = Loader({ paths: { '': uri }, sharedGlobal: true,
+                        sandboxPrototype: { globalFoo: 5 }});
+
+  let program = main(loader, 'main');
+
+  assert.ok(program.globalFoo === 5, '`globalFoo` exists');
+};
+
+exports["test require#resolve"] = function(assert) {
+  let foundRoot = require.resolve("sdk/tabs").replace(/sdk\/tabs.js$/, "");
+  assert.ok(root, foundRoot, "correct resolution root");
+
+  assert.equal(foundRoot + "sdk/tabs.js", require.resolve("sdk/tabs"), "correct resolution of sdk module");
+  assert.equal(foundRoot + "toolkit/loader.js", require.resolve("toolkit/loader"), "correct resolution of sdk module");
+
+  const localLoader = Loader({
+    paths: { "foo/bar": "bizzle",
+             "foo/bar2/": "bizzle2",
+             // Just to make sure this doesn't match the first entry,
+             // let use resolve this module
+             "foo/bar-bar": "foo/bar-bar" }
+  });
+  const localRequire = Require(localLoader, module);
+  assert.equal(localRequire.resolve("foo/bar"), "bizzle.js");
+  assert.equal(localRequire.resolve("foo/bar/baz"), "bizzle/baz.js");
+  assert.equal(localRequire.resolve("foo/bar-bar"), "foo/bar-bar.js");
+  assert.equal(localRequire.resolve("foo/bar2/"), "bizzle2.js");
+};
+
+const modulesURI = require.resolve("toolkit/loader").replace("toolkit/loader.js", "");
+exports["test loading a loader"] = function(assert) {
+  const loader = Loader({ paths: { "": modulesURI } });
+
+  const require = Require(loader, module);
+
+  const requiredLoader = require("toolkit/loader");
+
+  assert.equal(requiredLoader.Loader, Loader,
+               "got the same Loader instance");
+
+  const jsmLoader = Cu.import(require.resolve("toolkit/loader"), {}).Loader;
+
+  assert.equal(jsmLoader.Loader, requiredLoader.Loader,
+               "loading loader via jsm returns same loader");
+
+  unload(loader);
+};
+
+exports['test loader on unsupported modules with checkCompatibility true'] = function(assert) {
+  let loader = Loader({
+    paths: { '': root + "/" },
+    checkCompatibility: true
+  });
+  let require = Require(loader, module);
+
+  assert.throws(() => {
+    if (!app.is('Firefox')) {
+      require('fixtures/loader/unsupported/firefox');
+    }
+    else {
+      require('fixtures/loader/unsupported/fennec');
+    }
+  }, /^Unsupported Application/, "throws Unsupported Application");
+
+  unload(loader);
+};
+
+exports['test loader on unsupported modules with checkCompatibility false'] = function(assert) {
+  let loader = Loader({
+    paths: { '': root + "/" },
+    checkCompatibility: false
+  });
+  let require = Require(loader, module);
+
+  try {
+    if (!app.is('Firefox')) {
+      require('fixtures/loader/unsupported/firefox');
+    }
+    else {
+      require('fixtures/loader/unsupported/fennec');
+    }
+    assert.pass("loaded unsupported module without an error");
+  }
+  catch(e) {
+    assert.fail(e);
+  }
+
+  unload(loader);
+};
+
+exports['test loader on unsupported modules with checkCompatibility default'] = function(assert) {
+  let loader = Loader({ paths: { '': root + "/" } });
+  let require = Require(loader, module);
+
+  try {
+    if (!app.is('Firefox')) {
+      require('fixtures/loader/unsupported/firefox');
+    }
+    else {
+      require('fixtures/loader/unsupported/fennec');
+    }
+    assert.pass("loaded unsupported module without an error");
+  }
+  catch(e) {
+    assert.fail(e);
+  }
+
+  unload(loader);
+};
+
+exports["test Cu.import of toolkit/loader"] = (assert) => {
+  const toolkitLoaderURI = require.resolve("toolkit/loader");
+  const loaderModule = Cu.import(toolkitLoaderURI).Loader;
+  const { Loader, Require, Main } = loaderModule;
+  const version = "0.1.0";
+  const id = `fxos_${version.replace(".", "_")}_simulator@mozilla.org`;
+  const uri = `resource://${encodeURIComponent(id.replace("@", "at"))}/`;
+
+  const loader = Loader({
+    paths: {
+      "./": uri + "lib/",
+      // Can't just put `resource://gre/modules/commonjs/` as it
+      // won't take module overriding into account.
+      "": toolkitLoaderURI.replace("toolkit/loader.js", "")
+    },
+    globals: {
+      console: console
+    },
+    modules: {
+      "toolkit/loader": loaderModule,
+      addon: {
+        id: "simulator",
+        version: "0.1",
+        uri: uri
+      }
+    }
+  });
+
+  let require_ = Require(loader, { id: "./addon" });
+  assert.equal(typeof(loaderModule),
+               typeof(require_("toolkit/loader")),
+               "module returned is whatever was mapped to it");
+};
+
+exports["test Cu.import in b2g style"] = (assert) => {
+  const {FakeCu} = require("./loader/b2g");
+  const toolkitLoaderURI = require.resolve("toolkit/loader");
+  const b2g = new FakeCu();
+
+  const exported = {};
+  const loader = b2g.import(toolkitLoaderURI, exported);
+
+  assert.equal(typeof(exported.Loader),
+               "function",
+               "loader is a function");
+  assert.equal(typeof(exported.Loader.Loader),
+               "function",
+               "Loader.Loader is a funciton");
+};
+
+exports['test lazy globals'] = function (assert) {
+  let uri = root + '/fixtures/loader/lazy/';
+  let gotFoo = false;
+  let foo = {};
+  let modules = {
+    get foo() {
+      gotFoo = true;
+      return foo;
+    }
+  };
+  let loader = Loader({ paths: { '': uri }, modules: modules});
+  assert.ok(!gotFoo, "foo hasn't been accessed during loader instanciation");
+  let program = main(loader, 'main');
+  assert.ok(!gotFoo, "foo hasn't been accessed during module loading");
+  assert.equal(program.useFoo(), foo, "foo mock works");
+  assert.ok(gotFoo, "foo has been accessed only when we first try to use it");
+};
+
+exports['test user global'] = function(assert) {
+  // Test case for bug 827792
+  let com = {};
+  let loader = require('toolkit/loader');
+  let loadOptions = require('@loader/options');
+  let options = loader.override(loadOptions,
+                                {globals: loader.override(loadOptions.globals,
+                                                          {com: com,
+                                                           console: console,
+                                                           dump: dump})});
+  let subloader = loader.Loader(options);
+  let userRequire = loader.Require(subloader, module);
+  let userModule = userRequire("./loader/user-global");
+
+  assert.equal(userModule.getCom(), com,
+               "user module returns expected `com` global");
+};
+
+exports['test custom require caching'] = function(assert) {
+  const loader = Loader({
+    paths: { '': root + "/" },
+    requireHook: (id, require) => {
+      // Just load it normally
+      return require(id);
+    }
+  });
+  const require = Require(loader, module);
+
+  let data = require('fixtures/loader/json/mutation.json');
+  assert.equal(data.value, 1, 'has initial value');
+  data.value = 2;
+  let newdata = require('fixtures/loader/json/mutation.json');
+  assert.equal(
+    newdata.value,
+    2,
+    'JSON objects returned should be cached and the same instance'
+  );
+};
+
+exports['test caching when proxying a loader'] = function(assert) {
+  const parentRequire = require;
+  const loader = Loader({
+    paths: { '': root + "/" },
+    requireHook: (id, childRequire) => {
+      if(id === 'gimmejson') {
+        return childRequire('fixtures/loader/json/mutation.json')
+      }
+      // Load it with the original (global) require
+      return parentRequire(id);
+    }
+  });
+  const childRequire = Require(loader, module);
+
+  let data = childRequire('./fixtures/loader/json/mutation.json');
+  assert.equal(data.value, 1, 'data has initial value');
+  data.value = 2;
+
+  let newdata = childRequire('./fixtures/loader/json/mutation.json');
+  assert.equal(newdata.value, 2, 'data has changed');
+
+  let childData = childRequire('gimmejson');
+  assert.equal(childData.value, 1, 'data from child loader has initial value');
+  childData.value = 3;
+  let newChildData = childRequire('gimmejson');
+  assert.equal(newChildData.value, 3, 'data from child loader has changed');
+
+  data = childRequire('./fixtures/loader/json/mutation.json');
+  assert.equal(data.value, 2, 'data from parent loader has not changed');
+
+  // Set it back to the original value just in case (this instance
+  // will be shared across tests)
+  data.value = 1;
+}
+
+require('sdk/test').run(exports);