1 files changed, 128 insertions, 0 deletions
diff --git a/toolkit/components/telemetry/tests/browser/browser_media_element_in_page_scalar.js b/toolkit/components/telemetry/tests/browser/browser_media_element_in_page_scalar.js
new file mode 100644
index 0000000000..3c9dd8f8ee
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+++ b/toolkit/components/telemetry/tests/browser/browser_media_element_in_page_scalar.js
@@ -0,0 +1,128 @@
+"use strict";
+
+const { TelemetryTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TelemetryTestUtils.sys.mjs"
+);
+const LOCATION =
+  "https://example.com/browser/toolkit/components/telemetry/tests/browser/";
+const CORS_LOCATION =
+  "https://example.org/browser/toolkit/components/telemetry/tests/browser/";
+const MEDIA_SCALAR_NAME = "media.element_in_page_count";
+
+/**
+ * 'media.element_in_page_count' is a permanant scalar, this test is used to
+ * check if that scalar can be accumulated correctly under different situations.
+ */
+add_task(async function start_tests() {
+  // Clean all scalars first to prevent being interfered by former test.
+  TelemetryTestUtils.getProcessScalars("parent", false, true /* clear */);
+
+  await testMediaInPageScalar({
+    description: "load a page with one media element",
+    url: "file_media.html",
+    expectedScalarCount: 1,
+  });
+  await testMediaInPageScalar({
+    description: "load a page with multiple media elements",
+    url: "file_media.html",
+    options: {
+      createSecondMedia: true,
+    },
+    expectedScalarCount: 1,
+  });
+  await testMediaInPageScalar({
+    description: "load a page with media element created from iframe",
+    url: "file_iframe.html",
+    options: {
+      iframeUrl: "file_media.html",
+    },
+    expectedScalarCount: 1,
+  });
+  await testMediaInPageScalar({
+    description: "load a page with media element created from CORS iframe",
+    url: "file_iframe.html",
+    options: {
+      iframeUrl: "file_media.html",
+      CORSIframe: true,
+    },
+    expectedScalarCount: 1,
+  });
+  await testMediaInPageScalar({
+    description: "run multiple tabs, all loading media page",
+    url: "file_media.html",
+    options: {
+      tabNums: 2,
+    },
+    expectedScalarCount: 2,
+  });
+});
+
+async function testMediaInPageScalar({
+  description,
+  url,
+  options,
+  expectedScalarCount,
+} = {}) {
+  info(`media scalar should be undefined in the start`);
+  let scalars = TelemetryTestUtils.getProcessScalars("parent");
+  is(scalars[MEDIA_SCALAR_NAME], undefined, "has not created media scalar yet");
+
+  info(`run test '${description}'`);
+  url = LOCATION + url;
+  await runMediaPage(url, options);
+
+  info(`media scalar should be increased to ${expectedScalarCount}`);
+  scalars = TelemetryTestUtils.getProcessScalars(
+    "parent",
+    false,
+    true /* clear */
+  );
+  is(
+    scalars[MEDIA_SCALAR_NAME],
+    expectedScalarCount,
+    "media scalar count is correct"
+  );
+  info("============= Next Testcase =============");
+}
+
+/**
+ * The following are helper functions.
+ */
+async function runMediaPage(url, options = {}) {
+  const tabNums = options.tabNums ? options.tabNums : 1;
+  for (let idx = 0; idx < tabNums; idx++) {
+    info(`open a tab loading media page`);
+    const tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, url);
+    if (options.iframeUrl) {
+      let iframeURL = options.CORSIframe ? CORS_LOCATION : LOCATION;
+      iframeURL += options.iframeUrl;
+      await loadPageForIframe(tab, iframeURL);
+    }
+
+    if (options.createSecondMedia) {
+      info(`create second media in the page`);
+      await createMedia(tab);
+    }
+
+    info(`remove tab`);
+    await BrowserTestUtils.removeTab(tab);
+    await BrowserUtils.promiseObserved("window-global-destroyed");
+  }
+}
+
+function createMedia(tab) {
+  return SpecialPowers.spawn(tab.linkedBrowser, [], _ => {
+    const video = content.document.createElement("VIDEO");
+    video.src = "gizmo.mp4";
+    video.loop = true;
+    content.document.body.appendChild(video);
+  });
+}
+
+function loadPageForIframe(tab, url) {
+  return SpecialPowers.spawn(tab.linkedBrowser, [url], async url => {
+    const iframe = content.document.getElementById("iframe");
+    iframe.src = url;
+    await new Promise(r => (iframe.onload = r));
+  });
+}