1 files changed, 14 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webmessaging/message-channels/implied-start.any.js b/testing/web-platform/tests/webmessaging/message-channels/implied-start.any.js
new file mode 100644
index 0000000000..460d26b7e4
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/implied-start.any.js
@@ -0,0 +1,14 @@
+// META: title=onmessage implied start()
+
+async_test(function(t) {
+  var channel = new MessageChannel();
+  channel.port1.postMessage(1);
+  channel.port2.onmessage = function() {
+    setTimeout(t.step_func(function() {
+      t.done();
+    }), 50);
+    channel.port2.onmessage = t.step_func(function() {
+      assert_unreached();
+    });
+  }; // implies start()
+});