Convert Google Now's Authentication Manager to use Promises

chrome/browser/resources/google_now/common_test_util.js

 // Copyright 2013 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.
 
 // Common test utilities.
 
 /**
  * Allows console.log output.
  */
 var showConsoleLogOutput = false;
@@ skipping 64 matching lines @@
 /**
  * MockPromise
  * The JS test harness expects all calls to complete synchronously.
  * As a result, we can't use built-in JS promises since they run asynchronously.
  * Instead of mocking all possible calls to promises, a skeleton
  * implementation is provided to get the tests to pass.
  */
 var Promise = function() {
   function PromisePrototypeObject(asyncTask) {
     var result;
+    var resolved = false;
     asyncTask(
         function(asyncResult) {
           result = asyncResult;
+          resolved = true;
         },
-        function() {}); // Errors are unsupported.
+        function(asyncFailureResult) {
+          result = asyncResult;
+          resolved = false;
+        });
 
     function then(callback) {
-      callback.call(null, result);
+      if (resolved) {
+        callback.call(null, result);
+      }
+      return this;
     }
-    return {then: then, isPromise: true};
+
+    // Promises use the function name catch to call back error handlers.

[skare_, 2014/02/13 23:53:52]

(no action required, just a suggestion based on first reading)
maybe put "catch" in quotes, like:
// Promises call "catch" to ...
// Promises use the function named "catch"

[robliao, 2014/02/14 00:05:11]

Done.

+    // We can't use catch since function or variable names cannot use the word

[skare_, 2014/02/13 23:53:52]

or just "We can't use 'catch' since it's reserved"

[robliao, 2014/02/14 00:05:11]

This isn't strictly true, since it works fine for foo.catch.
Object initialization, function names, and variable names are the few instances
I've found thus far that do not allow this. Variable references, function calls,
on the other hand, are okay.

+    // catch.
+    function catchFunc(callback) {
+      if (!resolved) {
+        callback.call(null, result);
+      }
+      return this;
+    }
+
+    var promiseObj = {then: then, isPromise: true};
+    // Using the name 'catch' above during initialization will trigger an error.
+    promiseObj.catch = catchFunc;

[skare_, 2014/02/13 23:37:03]

does promiseObj.catch = function(...) {} work?

[robliao, 2014/02/13 23:43:20]

It does, but the named functions follows other non-prototype based 'classes' we
have floating around in Google Now.
On 2014/02/13 23:37:03, Travis Skare wrote:

[skare_, 2014/02/13 23:53:52]

return {then: then, isPromise: true, catch: catchFunc} ?

[robliao, 2014/02/14 00:05:11]

This won't work since "catch" is reserved in object initialization.

[skare_, 2014/02/14 00:19:26]

will catch* you in person since I might have constructed the full parallel
example wrong, but this seems ok?
x = function() { return {catch: function(){return 'hi'} }}; (new x).catch()

*sincere apologies

[robliao, 2014/02/14 01:57:04]

And done.
On 2014/02/14 00:19:26, Travis Skare wrote:

+    return promiseObj;
   }
 
   function all(arrayOfPromises) {
     var results = [];
     for (i = 0; i < arrayOfPromises.length; i++) {
       if (arrayOfPromises[i].isPromise) {
         arrayOfPromises[i].then(function(result) {
           results[i] = result;
         });
       } else {
         results[i] = arrayOfPromises[i];
       }
     }
     var promise = new PromisePrototypeObject(function(resolve) {
       resolve(results);
     });
     return promise;
   }
   PromisePrototypeObject.all = all;
   return PromisePrototypeObject;
 }();