1 files changed, 24 insertions, 0 deletions
diff --git a/testing/web-platform/tests/portals/portals-activate-twice.html b/testing/web-platform/tests/portals/portals-activate-twice.html
new file mode 100644
index 0000000000..0eea5465a2
--- /dev/null
+++ b/testing/web-platform/tests/portals/portals-activate-twice.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+promise_test(async t => {
+  assert_implements("HTMLPortalElement" in self);
+  let waitForMessage = new Promise((resolve, reject) => {
+    window.onmessage = e => resolve(e.data);
+  });
+  window.open("resources/portal-activate-twice-window-1.html");
+  let error = await waitForMessage;
+  assert_equals(error, "InvalidStateError");
+}, "Calling activate when a portal is already activating should fail");
+
+promise_test(async t => {
+  assert_implements("HTMLPortalElement" in self);
+  let waitForMessage = new Promise((resolve, reject) => {
+    window.onmessage = e => resolve(e.data);
+  });
+  window.open("resources/portal-activate-twice-window-2.html");
+  let error = await waitForMessage;
+  assert_equals(error, "InvalidStateError");
+});
+</script>