forked from mirrors/gecko-dev
50 lines
1.7 KiB
JavaScript
50 lines
1.7 KiB
JavaScript
"use strict";
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/**
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* WHOA THERE: We should never be adding new things to EXPECTED_REFLOWS. This
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* is a whitelist that should slowly go away as we improve the performance of
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* the front-end. Instead of adding more reflows to the whitelist, you should
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* be modifying your code to avoid the reflow.
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*
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* See https://developer.mozilla.org/en-US/Firefox/Performance_best_practices_for_Firefox_fe_engineers
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* for tips on how to do that.
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*/
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const EXPECTED_REFLOWS = [
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/**
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* Nothing here! Please don't add anything new!
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*/
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];
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/**
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* This test ensures that there are no unexpected
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* uninterruptible reflows when closing windows. When the
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* window is closed, the test waits until the original window
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* has activated.
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*/
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add_task(async function() {
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// Ensure that this browser window starts focused. This seems to be
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// necessary to avoid intermittent failures when running this test
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// on repeat.
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await new Promise(resolve => {
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waitForFocus(resolve, window);
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});
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let win = await BrowserTestUtils.openNewBrowserWindow();
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await new Promise(resolve => {
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waitForFocus(resolve, win);
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});
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// At the time of writing, there are no reflows on window closing.
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// Mochitest will fail if we have no assertions, so we add one here
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// to make sure nobody adds any new ones.
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Assert.equal(EXPECTED_REFLOWS.length, 0,
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"We shouldn't have added any new expected reflows for window close.");
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await withReflowObserver(async function() {
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let promiseOrigBrowserFocused = BrowserTestUtils.waitForCondition(() => {
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return Services.focus.activeWindow == window;
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});
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await BrowserTestUtils.closeWindow(win);
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await promiseOrigBrowserFocused;
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}, EXPECTED_REFLOWS, win);
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});
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