<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Selectors Test: :has(:nth-child()) invalidation for sibling change</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<link rel="help" href="https://drafts.csswg.org/selectors/#relational">
<style>
  #test-container > div { background-color: green; }
  #target1:has(.item:nth-child(3)) { background-color: red; }
  #target2:has(.item:nth-last-child(3)) { background-color: red; }
  #target3:has(.item:nth-child(3) > .child) { background-color: red; }
  #target4:has(.item:nth-last-child(3) > .child) { background-color: red; }
</style>
<div id="test-container">
  <div id="target1">
    <div class="item" id="item1">FAIL if you see this text</div>
    <div class="item"></div>
    <div class="item">This text should have a green background</div>
  </div>
  <div id="target2">
    <div class="item">This text should have a green background</div>
    <div class="item"></div>
    <div class="item" id="item2">FAIL if you see this text</div>
  </div>
  <div id="target3">
    <div class="item" id="item3">FAIL if you see this text</div>
    <div class="item"></div>
    <div class="item">
      <span class="child">This text should have a green background<span>
    </div>
  </div>
  <div id="target4">
    <div class="item">
      <span class="child">This text should have a green background<span>
    </div>
    <div class="item"></div>
    <div class="item" id="item4">FAIL if you see this text</div>
  </div>
</div>
<script>
  test(() => {
    assert_equals(getComputedStyle(target1).backgroundColor, "rgb(255, 0, 0)");
    assert_equals(getComputedStyle(target2).backgroundColor, "rgb(255, 0, 0)");
    assert_equals(getComputedStyle(target3).backgroundColor, "rgb(255, 0, 0)");
    assert_equals(getComputedStyle(target4).backgroundColor, "rgb(255, 0, 0)");
  }, "Initially red");

  test(() => {
    item1.remove();
    assert_equals(getComputedStyle(target1).backgroundColor, "rgb(0, 128, 0)");
  }, ":nth-child() no longer matching after removal");

  test(() => {
    item2.remove();
    assert_equals(getComputedStyle(target2).backgroundColor, "rgb(0, 128, 0)");
  }, ":nth-last-child() no longer matching after removal");

  test(() => {
    item3.remove();
    assert_equals(getComputedStyle(target3).backgroundColor, "rgb(0, 128, 0)");
  }, ":nth-child() in non-subject no longer matching after removal");

  test(() => {
    item4.remove();
    assert_equals(getComputedStyle(target4).backgroundColor, "rgb(0, 128, 0)");
  }, ":nth-last-child() in non-subject no longer matching after removal");
</script>
