Bug 1413836 - Add a test to ensure :focus is applied to host when the focus is moved by <tab> r=smaug

Depends on D123863 Differential Revision: https://phabricator.services.mozilla.com/D124067
2021-09-07 15:01:37 +00:00 · 2021-09-07 15:01:37 +00:00 · 52f868d839
--- a/testing/web-platform/tests/shadow-dom/focus/focus-tab-on-shadow-host.html
+++ b/testing/web-platform/tests/shadow-dom/focus/focus-tab-on-shadow-host.html
@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Test: Use tab to navigate the focus to an element inside shadow host with delegatesFocus</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="resources/shadow-utils.js"></script>
+
+<body>
+  <div id="host"></div>
+</body>
+
+<script>
+const host = document.getElementById("host");
+
+const shadowRoot = host.attachShadow({ mode: "open", delegatesFocus: true });
+const input = document.createElement("input");
+shadowRoot.appendChild(input);
+
+promise_test(async function() {
+  assert_equals(document.activeElement, document.body);
+  // Press <tab>
+  await navigateFocusForward();
+  assert_equals(document.activeElement, host);
+  assert_equals(shadowRoot.activeElement, input);
+  assert_true(host.matches(':focus'));
+}, ":focus should be applied to the host when the focus is moved by <tab>");
+</script>