chromium/third_party/blink/web_tests/external/wpt/css/selectors/invalidation/has-side-effect.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Selector Invalidation: Invalidate :has() as result of insertion/removal</title>
<link rel="author" title="David Shin" href="mailto:[email protected]">
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:[email protected]">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<link rel="help" href="https://drafts.csswg.org/selectors/#relational">
<style>
div, main { color: grey }
#subject:has(+ #next_sibling) { color: red; }
#prev_sibling:has(+ #subject + #next_sibling) { color: green; }
</style>

<main id=main>
  <div id=prev_sibling></div>
  <div id=subject></div>
  <div id=blocks_match></div>
  <div id=next_sibling></div>
</main>

<script>
const grey = 'rgb(128, 128, 128)';
const red = 'rgb(255, 0, 0)';
const green = 'rgb(0, 128, 0)';

function testColors(test_name, subject_color, prev_sibling_color) {
    test(function() {
        assert_equals(getComputedStyle(subject).color, subject_color);
        assert_equals(getComputedStyle(prev_sibling).color, prev_sibling_color);
    }, test_name);
}

testColors('Initial colors', grey, grey);

const d = blocks_match;
d.remove();

testColors('Matches after #blocks_match removed', red, green);
subject.after(d);

testColors('Does not match after #blocks_match added', grey, grey);
</script>