css/css-shadow/slotted-nested.html

<!doctype html>
<link rel="href" href="https://mozilla.org" title="Mozilla">
<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
<link rel="help" href="https://drafts.csswg.org/css-shadow/#slotted-pseudo">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="host"><p>This text should be green</p></div>
<script>
  let shadow = host.attachShadow({ mode: "open" });
  shadow.innerHTML = `
    <style>
      /* This is not expected to match */
      .container ::slotted(p) {
        color: red !important;
      }

      /* This _is_ expected to match */
      #nested ::slotted(p) {
        background-color: green;
      }
    </style>
    <div id="nested"><slot></slot></div>
  `;

  let nested = shadow.querySelector("#nested").attachShadow({ mode: "open" });
  nested.innerHTML = `
    <style>
      .container ::slotted(p) {
        color: green;
      }
    </style>
    <div class="container">
      <slot></slot>
    </div>
  `;

  let p = document.querySelector("p");
  test(function() {
    assert_equals(getComputedStyle(p).color, "rgb(0, 128, 0)");
    assert_equals(getComputedStyle(p).backgroundColor, "rgb(0, 128, 0)");
  }, "Slotted matches rules against the slot in the right tree");
  test(function() {
    nested.querySelector(".container").classList.remove("container");
    assert_not_equals(getComputedStyle(p).color, "rgb(0, 128, 0)");

    nested.host.removeAttribute("id");
    assert_not_equals(getComputedStyle(p).backgroundColor, "rgb(0, 128, 0)");
  }, "Style invalidation works correctly for nested slots");
</script>