1 files changed, 82 insertions, 0 deletions
diff --git a/services/common/tests/unit/test_observers.js b/services/common/tests/unit/test_observers.js
new file mode 100644
index 0000000000..b0fce95e0b
--- /dev/null
+++ b/services/common/tests/unit/test_observers.js
@@ -0,0 +1,82 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const { Observers } = ChromeUtils.importESModule(
+  "resource://services-common/observers.sys.mjs"
+);
+
+var gSubject = {};
+
+add_test(function test_function_observer() {
+  let foo = false;
+
+  let onFoo = function (subject, data) {
+    foo = !foo;
+    Assert.equal(subject, gSubject);
+    Assert.equal(data, "some data");
+  };
+
+  Observers.add("foo", onFoo);
+  Observers.notify("foo", gSubject, "some data");
+
+  // The observer was notified after being added.
+  Assert.ok(foo);
+
+  Observers.remove("foo", onFoo);
+  Observers.notify("foo");
+
+  // The observer was not notified after being removed.
+  Assert.ok(foo);
+
+  run_next_test();
+});
+
+add_test(function test_method_observer() {
+  let obj = {
+    foo: false,
+    onFoo(subject, data) {
+      this.foo = !this.foo;
+      Assert.equal(subject, gSubject);
+      Assert.equal(data, "some data");
+    },
+  };
+
+  // The observer is notified after being added.
+  Observers.add("foo", obj.onFoo, obj);
+  Observers.notify("foo", gSubject, "some data");
+  Assert.ok(obj.foo);
+
+  // The observer is not notified after being removed.
+  Observers.remove("foo", obj.onFoo, obj);
+  Observers.notify("foo");
+  Assert.ok(obj.foo);
+
+  run_next_test();
+});
+
+add_test(function test_object_observer() {
+  let obj = {
+    foo: false,
+    observe(subject, topic, data) {
+      this.foo = !this.foo;
+
+      Assert.equal(subject, gSubject);
+      Assert.equal(topic, "foo");
+      Assert.equal(data, "some data");
+    },
+  };
+
+  Observers.add("foo", obj);
+  Observers.notify("foo", gSubject, "some data");
+
+  // The observer is notified after being added.
+  Assert.ok(obj.foo);
+
+  Observers.remove("foo", obj);
+  Observers.notify("foo");
+
+  // The observer is not notified after being removed.
+  Assert.ok(obj.foo);
+
+  run_next_test();
+});