css/css-highlight-api/highlight-pseudo-computed.html

<!doctype html>
<meta charset="utf-8">
<title>CSS ::highlight Pseudo-Element Test: ::highlight selector getComputedStyle</title>
<link rel="help" href="https://drafts.csswg.org/css-highlight-api-1/">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  #target::highlight(foo) {
    background-color: green;
    color: lime;
  }
  #target::highlight(bar) {
    background-color: cyan;
    color: fuchsia;
  }
</style>
<div id="target"></div>
<script>
  let highlightPseudo = "::highlight(foo)";
  test(() => {
    let style = getComputedStyle(target, highlightPseudo);
    assert_equals(style.backgroundColor, "rgb(0, 128, 0)", "Background color is green.");
    assert_equals(style.color, "rgb(0, 255, 0)", "Color is lime.");
  }, `getComputedStyle() for ${highlightPseudo}`);

  highlightPseudo = "::highlight(bar)";
  test(() => {
    let style = getComputedStyle(target, highlightPseudo);
    assert_equals(style.backgroundColor, "rgb(0, 255, 255)", "Background color is cyan.");
    assert_equals(style.color, "rgb(255, 0, 255)", "Color is fuchsia.");
  }, `Different getComputedStyle() for ${highlightPseudo} and same element`);

  for (const illHighlightPseudo of ["::highlight(foo):", "::highlight(foo))", "::highlight(foo)(", "::highlight", "::highlight(foo)(foo)", "::highlight(foo)()", ":::highlight(foo)", "::highlight(foo).", "::highlight(foo,bar)"]) {
    test(() => {
      let style = getComputedStyle(target, illHighlightPseudo);
      let defaultStyle = getComputedStyle(target);
      assert_equals(style.backgroundColor, defaultStyle.backgroundColor, "Background color is element's default.");
      assert_equals(style.color,  defaultStyle.color, "Color is element's default.");
    }, `getComputedStyle() for ${illHighlightPseudo} should be element's default`);
  }
</script>