1 files changed, 68 insertions, 0 deletions
diff --git a/dom/performance/tests/test_worker_performance_now.js b/dom/performance/tests/test_worker_performance_now.js
new file mode 100644
index 0000000000..a22f66256e
--- /dev/null
+++ b/dom/performance/tests/test_worker_performance_now.js
@@ -0,0 +1,68 @@
+function ok(a, msg) {
+  dump("OK: " + !!a + "  =>  " + a + ": " + msg + "\n");
+  postMessage({ type: "status", status: !!a, msg: a + ": " + msg });
+}
+
+function workerTestDone() {
+  postMessage({ type: "finish" });
+}
+
+ok(self.performance, "Performance object should exist.");
+ok(
+  typeof self.performance.now == "function",
+  "Performance object should have a 'now' method."
+);
+var n = self.performance.now(),
+  d = Date.now();
+ok(n >= 0, "The value of now() should be equal to or greater than 0.");
+ok(
+  self.performance.now() >= n,
+  "The value of now() should monotonically increase."
+);
+
+// Spin on setTimeout() until performance.now() increases. Due to recent
+// security developments, the hr-time working group has not yet reached
+// consensus on what the recommend minimum clock resolution should be:
+// https://w3c.github.io/hr-time/#clock-resolution
+// Since setTimeout might return too early/late, our goal is for
+// performance.now() to increase before a 2 ms deadline rather than specific
+// number of setTimeout(N) invocations.
+// See bug 749894 (intermittent failures of this test)
+setTimeout(checkAfterTimeout, 1);
+
+var checks = 0;
+
+function checkAfterTimeout() {
+  checks++;
+  var d2 = Date.now();
+  var n2 = self.performance.now();
+
+  // Spin on setTimeout() until performance.now() increases. Abort the test
+  // if it runs for more than 2 ms or 50 timeouts.
+  let elapsedTime = d2 - d;
+  let elapsedPerf = n2 - n;
+  if (elapsedPerf == 0 && elapsedTime < 2 && checks < 50) {
+    setTimeout(checkAfterTimeout, 1);
+    return;
+  }
+
+  // Our implementation provides 1 ms resolution (bug 1451790), but we
+  // can't assert that elapsedPerf >= 1 ms because this worker test runs with
+  // "privacy.reduceTimerPrecision" == false so performance.now() is not
+  // limited to 1 ms resolution.
+  ok(
+    elapsedPerf > 0,
+    `Loose - the value of now() should increase after 2ms. ` +
+      `delta now(): ${elapsedPerf} ms`
+  );
+
+  // If we need more than 1 iteration, then either performance.now() resolution
+  // is shorter than 1 ms or setTimeout() is returning too early.
+  ok(
+    checks == 1,
+    `Strict - the value of now() should increase after one setTimeout. ` +
+      `iters: ${checks}, dt: ${elapsedTime}, now(): ${n2}`
+  );
+
+  workerTestDone();
+}