diff -r 000000000000 -r 6474c204b198 addon-sdk/source/test/test-observers.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/test/test-observers.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,123 @@
+/* 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";
+
+const { Loader } = require("sdk/test/loader");
+const { isWeak, WeakReference } = require("sdk/core/reference");
+const { subscribe, unsubscribe,
+        observe, Observer } = require("sdk/core/observer");
+const { Class } = require("sdk/core/heritage");
+
+const { Cc, Ci, Cu } = require("chrome");
+const { notifyObservers } = Cc["@mozilla.org/observer-service;1"].
+                              getService(Ci.nsIObserverService);
+
+const message = x => ({wrappedJSObject: x});
+
+exports["test subscribe unsubscribe"] = assert => {
+  const topic = Date.now().toString(32);
+  const Subscriber = Class({
+    extends: Observer,
+    initialize: function(observe) {
+      this.observe = observe;
+    }
+  });
+  observe.define(Subscriber, (x, subject, _, data) =>
+                                x.observe(subject.wrappedJSObject.x));
+
+  let xs = [];
+  const x = Subscriber((...rest) => xs.push(...rest));
+
+  let ys = [];
+  const y = Subscriber((...rest) => ys.push(...rest));
+
+  const publish = (topic, data) =>
+    notifyObservers(message(data), topic, null);
+
+  publish({x:0});
+
+  subscribe(x, topic);
+
+  publish(topic, {x:1});
+
+  subscribe(y, topic);
+
+  publish(topic, {x:2});
+  publish(topic + "!", {x: 2.5});
+
+  unsubscribe(x, topic);
+
+  publish(topic, {x:3});
+
+  subscribe(y, topic);
+
+  publish(topic, {x:4});
+
+  subscribe(x, topic);
+
+  publish(topic, {x:5});
+
+  unsubscribe(x, topic);
+  unsubscribe(y, topic);
+
+  publish(topic, {x:6});
+
+  assert.deepEqual(xs, [1, 2, 5]);
+  assert.deepEqual(ys, [2, 3, 4, 5]);
+}
+
+exports["test weak observers are GC-ed on unload"] = (assert, end) => {
+  const topic = Date.now().toString(32);
+  const loader = Loader(module);
+  const { Observer, observe,
+          subscribe, unsubscribe } = loader.require("sdk/core/observer");
+  const { isWeak, WeakReference } = loader.require("sdk/core/reference");
+
+  const MyObserver = Class({
+    extends: Observer,
+    initialize: function(observe) {
+      this.observe = observe;
+    }
+  });
+  observe.define(MyObserver, (x, ...rest) => x.observe(...rest));
+
+  const MyWeakObserver = Class({
+    extends: MyObserver,
+    implements: [WeakReference]
+  });
+
+  let xs = [];
+  let ys = [];
+  let x = new MyObserver((subject, topic, data) => {
+    xs.push(subject.wrappedJSObject, topic, data);
+  });
+  let y = new MyWeakObserver((subject, topic, data) => {
+    ys.push(subject.wrappedJSObject, topic, data);
+  });
+
+  subscribe(x, topic);
+  subscribe(y, topic);
+
+
+  notifyObservers(message({ foo: 1 }), topic, null);
+  x = null;
+  y = null;
+  loader.unload();
+
+  Cu.schedulePreciseGC(() => {
+
+    notifyObservers(message({ bar: 2 }), topic, ":)");
+
+    assert.deepEqual(xs, [{ foo: 1 }, topic, null,
+                          { bar: 2 }, topic, ":)"],
+                     "non week observer is kept");
+
+    assert.deepEqual(ys, [{ foo: 1 }, topic, null],
+                     "week observer was GC-ed");
+
+    end();
+  });
+};
+
+require("sdk/test").run(exports);
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