1 files changed, 30 insertions, 0 deletions
diff --git a/testing/web-platform/tests/dom/events/shadow-relatedTarget.html b/testing/web-platform/tests/dom/events/shadow-relatedTarget.html
new file mode 100644
index 0000000000..713555b7d8
--- /dev/null
+++ b/testing/web-platform/tests/dom/events/shadow-relatedTarget.html
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<!--
+  This test is adopted from Olli Pettay's test case at
+  http://mozilla.pettay.fi/shadow_focus.html
+-->
+<div id="host"></div>
+<input id="lightInput">
+<script>
+const root = host.attachShadow({ mode: "closed" });
+root.innerHTML = "<input id='shadowInput'>";
+
+async_test((test) => {
+  root.getElementById("shadowInput").focus();
+  window.addEventListener("focus", test.step_func_done((e) => {
+    assert_equals(e.relatedTarget, host);
+  }, "relatedTarget should be pointing to shadow host."), true);
+  lightInput.focus();
+}, "relatedTarget should not leak at capturing phase, at window object.");
+
+async_test((test) => {
+  root.getElementById("shadowInput").focus();
+  lightInput.addEventListener("focus", test.step_func_done((e) => {
+    assert_equals(e.relatedTarget, host);
+  }, "relatedTarget should be pointing to shadow host."), true);
+  lightInput.focus();
+}, "relatedTarget should not leak at target.");
+
+</script>