fune/browser/base/content/test/performance/browser_tabopen_reflows.js
2017-07-28 09:21:53 +02:00

44 lines
1.5 KiB
JavaScript

/* Any copyright is dedicated to the Public Domain.
http://creativecommons.org/publicdomain/zero/1.0/ */
"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 = [
// selection change notification may cause querying the focused editor content
// by IME and that will cause reflow.
{
stack: [
"select@chrome://global/content/bindings/textbox.xml",
],
}
];
/*
* This test ensures that there are no unexpected
* uninterruptible reflows when opening new tabs.
*/
add_task(async function() {
await ensureNoPreloadedBrowser();
// Add a reflow observer and open a new tab.
await withReflowObserver(async function() {
let switchDone = BrowserTestUtils.waitForEvent(window, "TabSwitchDone");
BrowserOpenTab();
await BrowserTestUtils.waitForEvent(gBrowser.selectedTab, "transitionend",
false, e => e.propertyName === "max-width");
await switchDone;
}, EXPECTED_REFLOWS);
let switchDone = BrowserTestUtils.waitForEvent(window, "TabSwitchDone");
await BrowserTestUtils.removeTab(gBrowser.selectedTab);
await switchDone;
});