layout/style/test/test_stylesheet_additions.html
author Sandor Molnar <smolnar@mozilla.com>
Fri, 24 Sep 2021 00:43:42 +0300
changeset 593102 4eda9eb8926bdd50f4b80128ce3475eb7c6d9a4d
parent 402407 4fef754d27619d28340ddcf86dcbcda7694af4fb
permissions -rw-r--r--
Merge autoland to mozilla-central. a=merge

<!doctype html>
<meta charset="utf-8">
<title>
  Test for bug 1273303: Stylesheet additions and removals known to not
  affect the document don't trigger restyles
</title>
<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<div class="classScope">
  <div></div>
</div>
<div id="idScope">
  <div></div>
</div>
<!--
  We do it this way, using `disabled`, because appending stylesheets to the
  document marks a restyle for that <style> element as needed, so we can't
  accurately measure whether we've restyled or not.
-->
<style id="target" disabled></style>
<script>
SimpleTest.waitForExplicitFinish();
const utils = SpecialPowers.getDOMWindowUtils(window);
const TESTS = [
  { selector: ".nonexistentClassScope", restyle: false },
  { selector: ".nonexistentClassScope + div", restyle: true },
  { selector: ".nonexistentClassScope div + div", restyle: false },
  { selector: ".classScope", restyle: true },
  { selector: ".classScope div", restyle: true },
  { selector: "#idScope", restyle: true },
  { selector: "#nonexistentIdScope", restyle: false },
  { selector: "#nonexistentIdScope div + bar", restyle: false },
  { selector: "baz", restyle: false },
  { cssText: " ", restyle: false },
  { cssText: "@keyframes foo { from { color: green } to { color: red } } #whatever { animation-name: foo; }", restyle: false },
];

for (const test of TESTS) {
  let cssText = test.cssText ? test.cssText : (test.selector + " { color: green; }");
  target.innerHTML = cssText;

  document.body.offsetWidth;
  const prevGeneration = utils.restyleGeneration;

  target.disabled = true;

  document.body.offsetWidth;
  (test.restyle ? isnot : is)(utils.restyleGeneration, prevGeneration,
     `Stylesheet removal with ${cssText} should ${test.restyle ? "have" : "not have"} caused a restyle`);

  target.disabled = false; // Make the stylesheet effective.

  if (test.selector) {
    let element = document.querySelector(test.selector);
    if (element) {
      is(test.restyle, true, "How could we not expect a restyle?");
      is(getComputedStyle(element).color, "rgb(0, 128, 0)",
         "Element style should've changed appropriately");
    }
  }

  document.body.offsetWidth;
  (test.restyle ? isnot : is)(utils.restyleGeneration, prevGeneration,
     `Stylesheet addition with ${cssText} should ${test.restyle ? "have" : "not have"} caused a restyle`);
}

SimpleTest.finish();
</script>