diff -r 000000000000 -r 6474c204b198 toolkit/modules/tests/xpcshell/test_TelemetryTimestamps.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/modules/tests/xpcshell/test_TelemetryTimestamps.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,70 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const Cu = Components.utils;
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+Cu.import("resource://gre/modules/Services.jsm");
+
+// The @mozilla/xre/app-info;1 XPCOM object provided by the xpcshell test harness doesn't
+// implement the nsIAppInfo interface, which is needed by Services.jsm and TelemetryPing.jsm.
+// updateAppInfo() creates and registers a minimal mock app-info.
+Cu.import("resource://testing-common/AppInfo.jsm");
+updateAppInfo();
+
+function getSimpleMeasurementsFromTelemetryPing() {
+  return Cu.import("resource://gre/modules/TelemetryPing.jsm", {}).
+    TelemetryPing.getPayload().simpleMeasurements;
+}
+
+function run_test() {
+  do_test_pending();
+  const Telemetry = Services.telemetry;
+  Telemetry.asyncFetchTelemetryData(function () {
+    try {
+      actualTest();
+    }
+    catch(e) {
+      do_throw("Failed: " + e);
+    }
+    do_test_finished();
+  });
+}
+
+function actualTest() {
+  // Test the module logic
+  let tmp = {};
+  Cu.import("resource://gre/modules/TelemetryTimestamps.jsm", tmp);
+  let TelemetryTimestamps = tmp.TelemetryTimestamps;
+  let now = Date.now();
+  TelemetryTimestamps.add("foo");
+  do_check_true(TelemetryTimestamps.get().foo != null); // foo was added
+  do_check_true(TelemetryTimestamps.get().foo >= now); // foo has a reasonable value
+
+  // Add timestamp with value
+  // Use a value far in the future since TelemetryPing substracts the time of
+  // process initialization.
+  const YEAR_4000_IN_MS = 64060588800000;
+  TelemetryTimestamps.add("bar", YEAR_4000_IN_MS);
+  do_check_eq(TelemetryTimestamps.get().bar, YEAR_4000_IN_MS); // bar has the right value
+
+  // Can't add the same timestamp twice
+  TelemetryTimestamps.add("bar", 2);
+  do_check_eq(TelemetryTimestamps.get().bar, YEAR_4000_IN_MS); // bar wasn't overwritten
+
+  let threw = false;
+  try {
+    TelemetryTimestamps.add("baz", "this isn't a number");
+  } catch (ex) {
+    threw = true;
+  }
+  do_check_true(threw); // adding non-number threw
+  do_check_null(TelemetryTimestamps.get().baz); // no baz was added
+
+  // Test that the data gets added to the telemetry ping properly
+  let simpleMeasurements = getSimpleMeasurementsFromTelemetryPing();
+  do_check_true(simpleMeasurements != null); // got simple measurements from ping data
+  do_check_true(simpleMeasurements.foo > 1); // foo was included
+  do_check_true(simpleMeasurements.bar > 1); // bar was included
+  do_check_null(simpleMeasurements.baz); // baz wasn't included since it wasn't added
+}