1 files changed, 14 insertions, 0 deletions
diff --git a/testing/web-platform/tests/streams/queuing-strategies-size-function-per-global.window.js b/testing/web-platform/tests/streams/queuing-strategies-size-function-per-global.window.js
new file mode 100644
index 0000000000..0f869f13b3
--- /dev/null
+++ b/testing/web-platform/tests/streams/queuing-strategies-size-function-per-global.window.js
@@ -0,0 +1,14 @@
+const iframe = document.createElement('iframe');
+document.body.appendChild(iframe);
+
+for (const type of ['CountQueuingStrategy', 'ByteLengthQueuingStrategy']) {
+  test(() => {
+    const myQs = new window[type]({ highWaterMark: 1 });
+    const yourQs = new iframe.contentWindow[type]({ highWaterMark: 1 });
+    assert_not_equals(myQs.size, yourQs.size,
+                      'size should not be the same object');
+  }, `${type} size should be different for objects in different realms`);
+}
+
+// Cleanup the document to avoid messing up the result page.
+iframe.remove();