1 files changed, 19 insertions, 0 deletions
diff --git a/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/bailout-side-effects-synchronous-script.window.js b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/bailout-side-effects-synchronous-script.window.js
new file mode 100644
index 0000000000..fb26c70a9c
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/bailout-side-effects-synchronous-script.window.js
@@ -0,0 +1,19 @@
+// META: script=resources/document-open-side-effects.js
+
+async_test(t => {
+  const iframe = document.body.appendChild(document.createElement("iframe"));
+  t.add_cleanup(() => iframe.remove());
+  self.testSynchronousScript = t.step_func(() => {
+    // Here, the entry settings object is still the iframe's. Delay it in such
+    // a way that makes the entry settings object the top-level page's, but
+    // without delaying too much that the parser becomes inactive. A microtask
+    // is perfect as it's executed in "clean up after running script".
+    Promise.resolve().then(t.step_func_done(() => {
+      const origURL = iframe.contentDocument.URL;
+      assertDocumentIsReadyForSideEffectsTest(iframe.contentDocument, "active parser whose script nesting level is greater than 0");
+      assert_equals(iframe.contentDocument.open(), iframe.contentDocument);
+      assertOpenHasNoSideEffects(iframe.contentDocument, origURL, "active parser whose script nesting level is greater than 0");
+    }));
+  });
+  iframe.src = "resources/bailout-order-synchronous-script-frame.html";
+}, "document.open bailout should not have any side effects (active parser whose script nesting level is greater than 0)");