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diff --git a/testing/web-platform/tests/html/webappapis/scripting/events/compile-event-handler-symbol-unscopables.html b/testing/web-platform/tests/html/webappapis/scripting/events/compile-event-handler-symbol-unscopables.html
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+++ b/testing/web-platform/tests/html/webappapis/scripting/events/compile-event-handler-symbol-unscopables.html
@@ -0,0 +1,71 @@
+<!DOCTYPE html>
+<meta charset="UTF-8" />
+<title>Inline event handler scopes exclude unscopable properties</title>
+<link rel="author" title="ExE Boss" href="https://ExE-Boss.tech" />
+<link rel="help" href="https://html.spec.whatwg.org/multipage/webappapis.html#getting-the-current-value-of-the-event-handler" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<script>
+  "use strict";
+  window.testVariable = {};
+</script>
+
+<!-- test case 1: element, document, and window -->
+<div id="test1_target" onclick='
+  "use strict";
+
+  window.testResults.testVariable = testVariable;
+'></div>
+
+<script>
+  "use strict";
+
+  test(() => {
+    const results = window.testResults = {};
+
+    document[Symbol.unscopables].testVariable = true;
+    document.testVariable = "FAIL (document)";
+
+    document.getElementById("test1_target").click();
+    assert_equals(results.testVariable, window.testVariable);
+  }, "unscopable `document.testVariable` doesn't shadow `window.testVariable`");
+
+  test(() => {
+    const results = window.testResults = {};
+    const element = document.getElementById("test1_target");
+
+    element[Symbol.unscopables].testVariable = true;
+    element.testVariable = "FAIL (element)";
+
+    element.click();
+    assert_equals(results.testVariable, window.testVariable);
+  }, "unscopable `element.testVariable` doesn't shadow `window.testVariable`");
+</script>
+
+<!-- test case 2: element, form owner, document, and window -->
+<form id="test2_form_owner" onsubmit="return false;">
+  <!-- <button> is a form-associated element and has a form owner.
+      https://html.spec.whatwg.org/C/#form-associated-element -->
+  <button id="test2_target" onclick='
+    "use strict";
+
+    window.testResults.testVariable = testVariable;
+  '></button>
+</form>
+
+<script>
+  "use strict";
+
+  test(() => {
+    const results = window.testResults = {};
+    const element = document.getElementById("test2_target");
+    const formOwner = document.getElementById("test2_form_owner");
+
+    formOwner[Symbol.unscopables].testVariable = true;
+    formOwner.testVariable = "FAIL (formOwner)";
+
+    element.click();
+    assert_equals(results.testVariable, window.testVariable);
+  }, "unscopable `formOwner.testVariable` doesn't shadow `window.testVariable`")
+</script>