Lightweight asynchronous test helper.

dart/tests/compiler/dart2js_extra/async_helper.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 async_helper;
+
+/**
+ * Asynchronous test runner.
+ *
+ * [test] is a one argument function which must accept a one argument
+ * function (onDone).  The test function may start asynchronous tasks,
+ * and must call onDone exactly once when all asynchronous tasks have
+ * completed.  The argument to onDone is a bool which indicates
+ * success of the complete test.
+ */
+void asyncTest(void test(void onDone(bool success))) {
+  onDone(bool success) {
+    if (!success) throw 'test failed';
+    print('unittest-suite-success');
+  }
+  test(onDone);
+  print('unittest-suite-wait-for-done');
+}