1 files changed, 136 insertions, 0 deletions
diff --git a/browser/base/content/test/tabcrashed/browser_multipleCrashedTabs.js b/browser/base/content/test/tabcrashed/browser_multipleCrashedTabs.js
new file mode 100644
index 0000000000..f29b88edb6
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+++ b/browser/base/content/test/tabcrashed/browser_multipleCrashedTabs.js
@@ -0,0 +1,136 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// eslint-disable-next-line @microsoft/sdl/no-insecure-url
+const PAGE_1 = "http://example.com";
+// eslint-disable-next-line @microsoft/sdl/no-insecure-url
+const PAGE_2 = "http://example.org";
+// eslint-disable-next-line @microsoft/sdl/no-insecure-url
+const PAGE_3 = "http://example.net";
+
+/**
+ * Checks that a particular about:tabcrashed page has the attribute set to
+ * use the "multiple about:tabcrashed" UI.
+ *
+ * @param browser (<xul:browser>)
+ *   The browser to check.
+ * @param expected (Boolean)
+ *   True if we expect the "multiple" state to be set.
+ * @returns Promise
+ * @resolves undefined
+ *   When the check has completed.
+ */
+async function assertShowingMultipleUI(browser, expected) {
+  let showingMultiple = await SpecialPowers.spawn(browser, [], async () => {
+    return (
+      content.document.getElementById("main").getAttribute("multiple") == "true"
+    );
+  });
+  Assert.equal(showingMultiple, expected, "Got the expected 'multiple' state.");
+}
+
+/**
+ * Takes a Telemetry histogram snapshot and returns the sum of all counts.
+ *
+ * @param snapshot (Object)
+ *        The Telemetry histogram snapshot to examine.
+ * @return (int)
+ *         The sum of all counts in the snapshot.
+ */
+function snapshotCount(snapshot) {
+  return Object.values(snapshot.values).reduce((a, b) => a + b, 0);
+}
+
+/**
+ * Switches to a tab, crashes it, and waits for about:tabcrashed
+ * to load.
+ *
+ * @param tab (<xul:tab>)
+ *   The tab to switch to and crash.
+ * @returns Promise
+ * @resolves undefined
+ *   When about:tabcrashed is loaded.
+ */
+async function switchToAndCrashTab(tab) {
+  let browser = tab.linkedBrowser;
+
+  await BrowserTestUtils.switchTab(gBrowser, tab);
+  let tabcrashed = BrowserTestUtils.waitForEvent(
+    browser,
+    "AboutTabCrashedReady",
+    false,
+    null,
+    true
+  );
+  await BrowserTestUtils.crashFrame(browser);
+  await tabcrashed;
+}
+
+/**
+ * Tests that the appropriate pieces of UI in the about:tabcrashed pages
+ * are updated to reflect how many other about:tabcrashed pages there
+ * are.
+ */
+add_task(async function test_multiple_tabcrashed_pages() {
+  let histogram = Services.telemetry.getHistogramById(
+    "FX_CONTENT_CRASH_NOT_SUBMITTED"
+  );
+  histogram.clear();
+
+  let tab1 = await BrowserTestUtils.openNewForegroundTab(gBrowser, PAGE_1);
+  let browser1 = tab1.linkedBrowser;
+
+  let tab2 = await BrowserTestUtils.openNewForegroundTab(gBrowser, PAGE_2);
+  let browser2 = tab2.linkedBrowser;
+
+  let tab3 = await BrowserTestUtils.openNewForegroundTab(gBrowser, PAGE_3);
+  let browser3 = tab3.linkedBrowser;
+
+  await switchToAndCrashTab(tab1);
+  Assert.ok(tab1.hasAttribute("crashed"), "tab1 has crashed");
+  Assert.ok(!tab2.hasAttribute("crashed"), "tab2 has not crashed");
+  Assert.ok(!tab3.hasAttribute("crashed"), "tab3 has not crashed");
+
+  // Should not be showing UI for multiple tabs in tab1.
+  await assertShowingMultipleUI(browser1, false);
+
+  await switchToAndCrashTab(tab2);
+  Assert.ok(tab1.hasAttribute("crashed"), "tab1 is still crashed");
+  Assert.ok(tab2.hasAttribute("crashed"), "tab2 has crashed");
+  Assert.ok(!tab3.hasAttribute("crashed"), "tab3 has not crashed");
+
+  // tab1 and tab2 should now be showing UI for multiple tab crashes.
+  await assertShowingMultipleUI(browser1, true);
+  await assertShowingMultipleUI(browser2, true);
+
+  await switchToAndCrashTab(tab3);
+  Assert.ok(tab1.hasAttribute("crashed"), "tab1 is still crashed");
+  Assert.ok(tab2.hasAttribute("crashed"), "tab2 is still crashed");
+  Assert.ok(tab3.hasAttribute("crashed"), "tab3 has crashed");
+
+  // tab1 and tab2 should now be showing UI for multiple tab crashes.
+  await assertShowingMultipleUI(browser1, true);
+  await assertShowingMultipleUI(browser2, true);
+  await assertShowingMultipleUI(browser3, true);
+
+  BrowserTestUtils.removeTab(tab1);
+  await assertShowingMultipleUI(browser2, true);
+  await assertShowingMultipleUI(browser3, true);
+
+  BrowserTestUtils.removeTab(tab2);
+  await assertShowingMultipleUI(browser3, false);
+
+  BrowserTestUtils.removeTab(tab3);
+
+  // We only record the FX_CONTENT_CRASH_NOT_SUBMITTED probe if there
+  // was a single about:tabcrashed page at unload time, so we expect
+  // only a single entry for the probe for when we removed the last
+  // crashed tab.
+  await BrowserTestUtils.waitForCondition(() => {
+    return snapshotCount(histogram.snapshot()) == 1;
+  }, `Collected value should become 1.`);
+
+  histogram.clear();
+});