Added async_helper and fixed broken asynchronous test.

tests/async_helper.dart

+// Copyright (c) 2013, 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 async_helper;
+
+// This library is used for testing asynchronous tests.

[ahe, 2013/06/17 13:51:11]

This should be a documentation comment and go before the the library tag.

[kustermann, 2013/06/25 07:14:21]

Done.

+// If a test is asynchronous, it needs to notify the testing driver
+// about this (otherwise tests may get reported as passing [after main()
+// finished] even if the asynchronous operations fail).
+// Tests which can't use the unittest framework should use the helper functions
+// in this library.
+// This library provides two methods
+//  - asyncStart(): Needs to be called before an asynchronous operation is
+//                  scheduled.
+//  - asyncEnd(): Needs to be called as soon as the asynchronous operation
+//                ended.
+// After the last asyncStart() called was matched with a corresponding
+// asyncEnd() call, the testing driver will be notified that the tests is done.
+
+
+bool _initialized = false;
+int _asyncLevel = 0;
+
+void _throwError(String msg) {

[ahe, 2013/06/17 13:51:11]

This method is will create annoying stack traces.  I'd prefer if you do not
throw in this method (return the exception instead).

[kustermann, 2013/06/25 07:14:21]

Done.

+  throw new Exception('Fatal: $msg. This is most likely a bug in your test');
+}
+
+void asyncStart() {
+  if (_initialized && _asyncLevel == 0) {
+    _throwError('asyncStart() was called even though we are done with '
+                'testing.');

[kustermann, 2013/06/13 14:40:51]

I put these three assertions in, so we can catch if a test is broken.

+  }
+  if (!_initialized) {
+    print('unittest-suite-wait-for-done');
+    _initialized = true;
+  }
+  _asyncLevel++;
+}
+
+void asyncEnd() {
+  if (_asyncLevel <= 0) {
+    if (_initialized) {
+      _throwError('asyncEnd() was called before asyncStart().');
+    } else {
+      _throwError('asyncEnd() was called more often than asyncStart().');
+    }
+  }
+  _asyncLevel--;
+  if (_asyncLevel == 0) {
+    print('unittest-suite-done');
+  }
+}
+

[ahe, 2013/06/17 13:51:11]

Extra line at end of file.

[kustermann, 2013/06/25 07:14:21]

Done.