forked from mirrors/gecko-dev
44 lines
1.6 KiB
JavaScript
44 lines
1.6 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 new tabs.
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*/
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add_task(async function() {
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await ensureNoPreloadedBrowser();
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// Because the tab strip is a scrollable frame, we can't use the
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// default dirtying function from withReflowObserver and reliably
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// get reflows for the strip. Instead, we provide a node that's
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// already in the scrollable frame to dirty - in this case, the
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// original tab.
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let origTab = gBrowser.selectedTab;
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let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser);
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await BrowserTestUtils.waitForCondition(() => tab._fullyOpen);
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// Add a reflow observer and open a new tab.
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await withReflowObserver(async function() {
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let switchDone = BrowserTestUtils.waitForEvent(window, "TabSwitchDone");
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gBrowser.removeTab(tab, { animate: true });
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await BrowserTestUtils.waitForEvent(tab, "transitionend",
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false, e => e.propertyName === "max-width");
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await switchDone;
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}, EXPECTED_REFLOWS, window, origTab);
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is(EXPECTED_REFLOWS.length, 0, "No reflows are expected when closing a tab");
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});
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