1 files changed, 91 insertions, 0 deletions
diff --git a/dom/base/test/fullscreen/browser_fullscreen-newtab.js b/dom/base/test/fullscreen/browser_fullscreen-newtab.js
new file mode 100644
index 0000000000..af714b1248
--- /dev/null
+++ b/dom/base/test/fullscreen/browser_fullscreen-newtab.js
@@ -0,0 +1,91 @@
+"use strict";
+
+// This test tends to trigger a race in the fullscreen time telemetry,
+// where the fullscreen enter and fullscreen exit events (which use the
+// same histogram ID) overlap. That causes TelemetryStopwatch to log an
+// error.
+SimpleTest.ignoreAllUncaughtExceptions(true);
+
+const kPage =
+  "https://example.org/browser/" +
+  "dom/base/test/fullscreen/file_fullscreen-newtab.html";
+
+function getSizeMode() {
+  return document.documentElement.getAttribute("sizemode");
+}
+
+async function runTest() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: kPage,
+    },
+    async function (browser) {
+      let promiseFsEvents = SpecialPowers.spawn(browser, [], function () {
+        return new Promise(resolve => {
+          let countFsChange = 0;
+          let countFsError = 0;
+          function checkAndResolve() {
+            if (countFsChange > 0 && countFsError > 0) {
+              Assert.ok(
+                false,
+                "Got both fullscreenchange and fullscreenerror events"
+              );
+            } else if (countFsChange > 2) {
+              Assert.ok(false, "Got too many fullscreenchange events");
+            } else if (countFsError > 1) {
+              Assert.ok(false, "Got too many fullscreenerror events");
+            } else if (countFsChange == 2 || countFsError == 1) {
+              resolve();
+            }
+          }
+
+          content.document.addEventListener("fullscreenchange", () => {
+            ++countFsChange;
+            checkAndResolve();
+          });
+          content.document.addEventListener("fullscreenerror", () => {
+            ++countFsError;
+            checkAndResolve();
+          });
+        });
+      });
+      let promiseNewTab = BrowserTestUtils.waitForNewTab(
+        gBrowser,
+        "about:blank"
+      );
+      await BrowserTestUtils.synthesizeMouseAtCenter("#link", {}, browser);
+      let [newtab] = await Promise.all([promiseNewTab, promiseFsEvents]);
+      await BrowserTestUtils.removeTab(newtab);
+
+      // Ensure the browser exits fullscreen state in reasonable time.
+      await Promise.race([
+        BrowserTestUtils.waitForCondition(() => getSizeMode() == "normal"),
+        // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+        new Promise(resolve => setTimeout(resolve, 2000)),
+      ]);
+
+      ok(!window.fullScreen, "The chrome window should not be in fullscreen");
+      ok(
+        !document.fullscreen,
+        "The chrome document should not be in fullscreen"
+      );
+    }
+  );
+}
+
+add_task(async function () {
+  await pushPrefs(
+    ["full-screen-api.transition-duration.enter", "0 0"],
+    ["full-screen-api.transition-duration.leave", "0 0"]
+  );
+  await runTest();
+});
+
+add_task(async function () {
+  await pushPrefs(
+    ["full-screen-api.transition-duration.enter", "200 200"],
+    ["full-screen-api.transition-duration.leave", "200 200"]
+  );
+  await runTest();
+});