diff --git a/testing/web-platform/tests/dom/events/legacy-pre-activation-behavior.window.js b/testing/web-platform/tests/dom/events/legacy-pre-activation-behavior.window.js
new file mode 100644
index 0000000000000..e9e84bfad1e6f
--- /dev/null
+++ b/testing/web-platform/tests/dom/events/legacy-pre-activation-behavior.window.js
@@ -0,0 +1,10 @@
+test(t => {
+  const input = document.body.appendChild(document.createElement('input'));
+  input.type = "radio";
+  t.add_cleanup(() => input.remove());
+  const clickEvent = new MouseEvent('click', { button: 0, which: 1 });
+  input.addEventListener('change', t.step_func(() => {
+    assert_equals(clickEvent.eventPhase, Event.NONE);
+  }));
+  input.dispatchEvent(clickEvent);
+}, "Use NONE phase during legacy-pre-activation behavior");