Bug 1583431 - Test "No Stack Sampling" feature - r=julienw

Differential Revision: https://phabricator.services.mozilla.com/D49234

--HG--
extra : moz-landing-system : lando

tools/profiler/tests/browser/browser.ini

@@ -9,6 +9,7 @@ support-files =
 
 [browser_test_feature_ipcmessages.js]
 [browser_test_feature_jsallocations.js]
+[browser_test_feature_nostacksampling.js]
 [browser_test_feature_preferencereads.js]
 [browser_test_feature_nativeallocations.js]
 [browser_test_profile_single_frame_page_info.js]

tools/profiler/tests/browser/browser_test_feature_nostacksampling.js

@@ -0,0 +1,78 @@
+/* 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 the No Stack Sampling feature.
+ */
+add_task(async function test_profile_feature_nostacksampling() {
+  if (!AppConstants.MOZ_GECKO_PROFILER) {
+    return;
+  }
+  Assert.ok(
+    !Services.profiler.IsActive(),
+    "The profiler is not currently active"
+  );
+
+  startProfiler({ features: ["threads", "js", "nostacksampling"] });
+
+  const url = BASE_URL + "do_work_500ms.html";
+  await BrowserTestUtils.withNewTab(url, async contentBrowser => {
+    const contentPid = await ContentTask.spawn(
+      contentBrowser,
+      null,
+      () => Services.appinfo.processID
+    );
+
+    // Wait 500ms so that the tab finishes executing.
+    await wait(500);
+
+    // Check that we can get no stacks when the feature is turned on.
+    {
+      const {
+        parentThread,
+        contentThread,
+      } = await stopProfilerNowAndGetThreads(contentPid);
+      Assert.equal(
+        parentThread.samples.data.length,
+        0,
+        "Stack samples were recorded from the parent process' main thread" +
+          "when the No Stack Sampling feature was turned on."
+      );
+      Assert.equal(
+        contentThread.samples.data.length,
+        0,
+        "Stack samples were recorded from the content process' main thread" +
+          "when the No Stack Sampling feature was turned on."
+      );
+    }
+
+    // Flush out any straggling allocation markers that may have not been collected
+    // yet by starting and stopping the profiler once.
+    startProfiler({ features: ["threads", "js"] });
+
+    // Now reload the tab with a clean run.
+    gBrowser.reload();
+    await wait(500);
+
+    // Check that stack samples were recorded.
+    {
+      const { parentThread, contentThread } = await stopProfilerAndGetThreads(
+        contentPid
+      );
+      Assert.greater(
+        parentThread.samples.data.length,
+        0,
+        "No Stack samples were recorded from the parent process' main thread" +
+          "when the No Stack Sampling feature was not turned on."
+      );
+
+      Assert.greater(
+        contentThread.samples.data.length,
+        0,
+        "No Stack samples were recorded from the content process' main thread" +
+          "when the No Stack Sampling feature was not turned on."
+      );
+    }
+  });
+});