1 files changed, 50 insertions, 0 deletions
diff --git a/tools/profiler/tests/xpcshell/test_responsiveness.js b/tools/profiler/tests/xpcshell/test_responsiveness.js
new file mode 100644
index 0000000000..5f57173090
--- /dev/null
+++ b/tools/profiler/tests/xpcshell/test_responsiveness.js
@@ -0,0 +1,50 @@
+/* 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/. */
+
+/**
+ * Test that we can measure non-zero event delays
+ */
+
+add_task(async () => {
+  const entries = 10000;
+  const interval = 1;
+  const threads = [];
+  const features = [];
+
+  await Services.profiler.StartProfiler(entries, interval, features, threads);
+
+  await functionA();
+
+  const profile = await stopNowAndGetProfile();
+  const [thread] = profile.threads;
+  const { samples } = thread;
+  const message = "eventDelay > 0 not found.";
+  let SAMPLE_STACK_SLOT = thread.samples.schema.eventDelay;
+
+  for (let i = 0; i < samples.data.length; i++) {
+    if (samples.data[i][SAMPLE_STACK_SLOT] > 0) {
+      Assert.ok(true, message);
+      return;
+    }
+  }
+  Assert.ok(false, message);
+});
+
+function doSyncWork(milliseconds) {
+  const start = Date.now();
+  while (true) {
+    this.n = 0;
+    for (let i = 0; i < 1e5; i++) {
+      this.n += Math.random();
+    }
+    if (Date.now() - start > milliseconds) {
+      return;
+    }
+  }
+}
+
+async function functionA() {
+  doSyncWork(100);
+  return captureAtLeastOneJsSample();
+}