WebUI: Replace cr.sendWithCallback with cr.sendWithPromise.

chrome/test/data/webui/webui_resource_async_browsertest.js

+// Copyright 2015 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.
+
+/**
+ * @fileoverview Framework for running async JS tests for cr.js utility methods.
+ */
+
+/** @const {string} Path to source root. */
+var ROOT_PATH = '../../../../';
+
+/** @const {string} Name of the chrome.send() message to be used in tests. */
+var CHROME_SEND_NAME = 'echoMessage';
+
+/**
+ * Test fixture for testing async methods of cr.js.
+ * @constructor
+ * @extends testing.Test
+ */
+function WebUIResourceAsyncTest() {}
+
+WebUIResourceAsyncTest.prototype = {
+  __proto__: testing.Test.prototype,
+
+  /** @override */
+  browsePreload: DUMMY_URL,
+
+  /** @override */
+  isAsync: true,
+
+  /** @override */
+  runAccessibilityChecks: false,
+
+  /** @override */
+  extraLibraries: [
+    ROOT_PATH + 'third_party/mocha/mocha.js',
+    ROOT_PATH + 'chrome/test/data/webui/mocha_adapter.js',
+    ROOT_PATH + 'ui/webui/resources/js/cr.js',
+  ],
+};
+
+TEST_F('WebUIResourceAsyncTest', 'SendWithPromise', function() {
+  /**
+   * TODO(dpapad): Move this helper method in test_api.js.
+   * @param {string} name chrome.send message name.
+   * @return {!Promise} Fires when chrome.send is called with the given message
+   *     name.
+   */
+  function whenChromeSendCalled(name) {
+    return new Promise(function(resolve, reject) {
+      registerMessageCallback(name, null, resolve);
+    });
+  }
+
+  suite('cr.js', function() {
+    setup(function() {
+      // Simulate a WebUI handler that echoes back all parameters passed to it.
+      whenChromeSendCalled(CHROME_SEND_NAME).then(function(args) {
+        assertEquals('cr.webUIResponse', args[0]);
+        var globalCallbackArgs = args.slice(1);
+        cr.webUIResponse.apply(null, globalCallbackArgs);
+      });
+    });
+
+    test('sendWithPromise_MultipleArgs', function() {
+      return cr.sendWithPromise(CHROME_SEND_NAME, 'foo', 'bar').then(
+          function(response) {
+            assertEquals(['foo', 'bar'].join(), response.join());

[Dan Beam, 2016/01/26 00:54:52]

in this case I don't think it's suitable for me to object to this, even if it's
not my personal style.  it's hard for you to know when I'm *not* objecting to
things that I would write differently.  assume I'm staying reserved most of the
time ;)

+          });
+    });
+
+    test('sendWithPromise_NoArgs', function() {
+      return cr.sendWithPromise(CHROME_SEND_NAME).then(function(response) {
+        assertEquals([].join(), response.join());
+      });
+    });
+  });
+
+  // Run all registered tests.
+  mocha.run();
+});