Never connect a port to the same frame

chrome/test/data/extensions/api_test/messaging/background_only/test.js

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var kPortErrorMessage =
+    'Could not establish connection. Receiving end does not exist.';
+
+// onMessage / onConnect in the same frame cannot be triggered by sendMessage or
+// connect, so both attempts to send a message should fail with an error.
+
+chrome.runtime.onMessage.addListener(function(msg, sender, sendResponse) {
+  chrome.test.fail('onMessage should not be triggered. Received: ' + msg);
+});
+
+chrome.runtime.onConnect.addListener(function(port) {
+  chrome.test.fail('onConnect should not be triggered. Port: ' + port.name);
+});
+
+chrome.test.runTests([
+  function sendMessageExpectingNoAnswer() {
+    chrome.runtime.sendMessage('hello without callback');
+    // The timer is here to try and get the test failure in the correct test
+    // case (namely "sendMessageExpectingNoAnswer"). If the timer is too short,
+    // but the test fails, then onMessage will still print an error that shows
+    // which test fails, but the test runner will think that it is running in
+    // the next test, and attribute the failure incorrectly.
+    setTimeout(chrome.test.callbackPass(), 100);
+  },
+
+  function sendMessageExpectingNoAnswerWithCallback() {
+    chrome.runtime.sendMessage('hello with callback',
+        chrome.test.callbackFail(kPortErrorMessage));
+  },
+
+  function connectAndDisconnect() {
+    chrome.runtime.connect({ name: 'The First Port'}).disconnect();
+    // Like sendMessageExpectingNoAnswer; onConnect should not be triggered.
+    setTimeout(chrome.test.callbackPass(), 100);
+  },
+
+  function connectExpectDisconnect() {
+    chrome.runtime.connect({ name: 'The Last Port'}).onDisconnect.addListener(
+        chrome.test.callbackFail(kPortErrorMessage));
+  },
+]);