Bug 1363505 - Add reflow test for window closing. r?florian
MozReview-Commit-ID: AmjNIldSQIz
--- a/browser/base/content/test/performance/browser.ini
+++ b/browser/base/content/test/performance/browser.ini
@@ -1,8 +1,9 @@
[DEFAULT]
support-files =
head.js
[browser_startup.js]
[browser_tabclose_reflows.js]
[browser_tabopen_reflows.js]
[browser_toolbariconcolor_restyles.js]
+[browser_windowclose_reflows.js]
[browser_windowopen_reflows.js]
new file mode 100644
--- /dev/null
+++ b/browser/base/content/test/performance/browser_windowclose_reflows.js
@@ -0,0 +1,50 @@
+"use strict";
+
+/**
+ * WHOA THERE: We should never be adding new things to EXPECTED_REFLOWS. This
+ * is a whitelist that should slowly go away as we improve the performance of
+ * the front-end. Instead of adding more reflows to the whitelist, you should
+ * be modifying your code to avoid the reflow.
+ *
+ * See https://developer.mozilla.org/en-US/Firefox/Performance_best_practices_for_Firefox_fe_engineers
+ * for tips on how to do that.
+ */
+const EXPECTED_REFLOWS = [
+ /**
+ * Nothing here! Please don't add anything new!
+ */
+];
+
+/**
+ * This test ensures that there are no unexpected
+ * uninterruptible reflows when closing windows. When the
+ * window is closed, the test waits until the original window
+ * has activated.
+ */
+add_task(function*() {
+ // Ensure that this browser window starts focused. This seems to be
+ // necessary to avoid intermittent failures when running this test
+ // on repeat.
+ yield new Promise(resolve => {
+ waitForFocus(resolve, window);
+ });
+
+ let win = yield BrowserTestUtils.openNewBrowserWindow();
+ yield new Promise(resolve => {
+ waitForFocus(resolve, win);
+ });
+
+ // At the time of writing, there are no reflows on window closing.
+ // Mochitest will fail if we have no assertions, so we add one here
+ // to make sure nobody adds any new ones.
+ Assert.equal(EXPECTED_REFLOWS.length, 0,
+ "We shouldn't have added any new expected reflows for window close.");
+
+ yield withReflowObserver(async function() {
+ let promiseOrigBrowserFocused = BrowserTestUtils.waitForCondition(() => {
+ return Services.focus.activeWindow == window;
+ });
+ await BrowserTestUtils.closeWindow(win);
+ await promiseOrigBrowserFocused;
+ }, EXPECTED_REFLOWS, win);
+});