Converting tests over to using event streams.

tests/html/postmessage_structured_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file
 
 library postmessage_js_test;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 import 'dart:html';
 import 'dart:collection';  // SplayTreeMap
 import 'utils.dart';
 
 injectSource(code) {
   final script = new ScriptElement();
   script.type = 'text/javascript';
   script.innerHtml = code;
   document.body.nodes.add(script);
 }
 
 main() {
   useHtmlConfiguration();
 
   test('js-to-dart-postmessage', () {
       // Pass an object literal from JavaScript. It should be seen as a Dart
       // Map.
 
       final JS_CODE = """
         window.postMessage({eggs: 3}, '*');
         """;
-      var callback;
-      var onSuccess = expectAsync1((e) {
-          window.on.message.remove(callback);
-        });
-      callback = (e) {
-        guardAsync(() {
-            var data = e.data;
-            if (data is String) return;    // Messages from unit test protocol.
-            expect(data, isMap);
-            expect(data['eggs'], equals(3));
-            onSuccess(e);
-          });
-      };
-      window.on.message.add(callback);
+      var completed = false;
+      var subscription = null;
+      subscription = window.onMessage.listen(expectAsyncUntil1(
+        (e) {
+          var data = e.data;
+          if (data is String) return;    // Messages from unit test protocol.
+          completed = true;
+          subscription.cancel();
+          expect(data, isMap);
+          expect(data['eggs'], equals(3));
+        },
+        () => completed));
       injectSource(JS_CODE);
     });
 
   test('dart-to-js-to-dart-postmessage', () {
       // Pass dictionaries between Dart and JavaScript.
 
       final JS_CODE = """
         window.addEventListener('message', handler);
         function handler(e) {
           var data = e.data;
           if (typeof data == 'string') return;
           if (data.recipient != 'JS') return;
           var response = {recipient: 'DART'};
           response[data['curry']] = 50;
           window.removeEventListener('message', handler);
           window.postMessage(response, '*');
         }
         """;
-      var callback;
-      var onSuccess = expectAsync1((e) {
-          window.on.message.remove(callback);
-        });
-      callback = (e) {
-        guardAsync(() {
-            var data = e.data;
-            if (data is String) return;    // Messages from unit test protocol.
-            expect(data, isMap);
-            if (data['recipient'] != 'DART') return;  // Hearing the sent message.
-            expect(data['peas'], equals(50));
-            onSuccess(e);
-          });
-      };
-      window.on.message.add(callback);
+      var completed = false;
+      var subscription = null;
+      subscription = window.onMessage.listen(expectAsyncUntil1(
+        (e) {
+          var data = e.data;
+          if (data is String) return;    // Messages from unit test protocol.
+          if (data['recipient'] != 'DART') return;  // Hearing the sent message.
+          completed = true;
+          subscription.cancel();
+          expect(data, isMap);
+          expect(data['peas'], equals(50));
+        },
+        () => completed));
       injectSource(JS_CODE);
       window.postMessage({'recipient': 'JS', 'curry': 'peas'}, '*');
     });
 
   go(testName, value) =>
       test(testName, () {
           // Round-trip graph from Dart to JavaScript and back.
 
           final JS_CODE = """
             window.addEventListener('message', handler);
             function handler(e) {
               var data = e.data;
               if (typeof data == 'string') return;
               if (data.recipient != 'JS') return;
               window.console.log(data.data);
               var response = {recipient: 'DART', data: data.data};
               window.removeEventListener('message', handler);
               window.postMessage(response, '*');
             }
             """;
-          var onSuccess = expectAsync0(() {});
-          callback(e) {
-            guardAsync(() {
-                var data = e.data;
-                if (data is String) return;    // Messages from unit test protocol.
-                expect(data, isMap);
-                if (data['recipient'] != 'DART') return;  // Not for me.
-                var returnedValue = data['data'];
-
-                window.on.message.remove(callback);
-                expect(returnedValue, isNot(same(value)));
-                verifyGraph(value, returnedValue);
-                onSuccess();
-              });
-          };
-          window.on.message.add(callback);
+          var completed = false;
+          var subscription = null;
+          subscription = window.onMessage.listen(expectAsyncUntil1(
+            (e) {
+              var data = e.data;
+              if (data is String) return;    // Messages from unit test protocol.

[Emily Fortuna, 2013/01/28 23:15:18]

delete one space here and you can get this line back to 80 char. :-)

+              if (data['recipient'] != 'DART') return;  // Not for me.
+              completed = true;
+              subscription.cancel();
+              expect(data, isMap);
+              var returnedValue = data['data'];
+              expect(returnedValue, isNot(same(value)));
+              verifyGraph(value, returnedValue);
+            },
+            () => completed));
           injectSource(JS_CODE);
           window.postMessage({'recipient': 'JS', 'data': value}, '*');
         });
 
   var obj1 = {'a': 100, 'b': 's'};
   var obj2 = {'x': obj1, 'y': obj1};  // DAG.
 
   var obj3 = {};
   obj3['a'] = 100;
   obj3['b'] = obj3;  // Cycle.
 
   var obj4 = new SplayTreeMap<String, dynamic>();  // Different implementation.
   obj4['a'] = 100;
   obj4['b'] = 's';
 
   var cyclic_list = [1, 2, 3];
   cyclic_list[1] = cyclic_list;
 
   go('test_simple_list', [1, 2, 3]);
   go('test_map', obj1);
   go('test_DAG', obj2);
   go('test_cycle', obj3);
   go('test_simple_splay', obj4);
   go('const_array_1', const [const [1], const [2]]);
   go('const_array_dag', const [const [1], const [1]]);
   go('array_deferred_copy', [1,2,3, obj3, obj3, 6]);
   go('array_deferred_copy_2', [1,2,3, [4, 5, obj3], [obj3, 6]]);
   go('cyclic_list', cyclic_list);
 }