Replace the existing unittest APIs with the new runner infrastructure.

test/returning_future_test.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 unittest.returning_future_test;
-
-import 'dart:async';
-
-import 'package:metatest/metatest.dart';
-import 'package:unittest/unittest.dart';
-
-void main() => initTests(_test);
-
-void _test(message) {
-  initMetatest(message);
-
-  expectTestResults('returning futures', () {
-    test("successful", () {
-      return new Future.sync(() {
-        expect(true, true);
-      });
-    });
-    // We repeat the fail and error tests, because during development
-    // I had a situation where either worked fine on their own, and
-    // error/fail worked, but fail/error would time out.
-    test("error1", () {
-      var callback = expectAsync(() {});
-      var excesscallback = expectAsync(() {});
-      return new Future.sync(() {
-        excesscallback();
-        excesscallback();
-        excesscallback();
-        callback();
-      });
-    });
-    test("fail1", () {
-      return new Future.sync(() {
-        expect(true, false);
-      });
-    });
-    test("error2", () {
-      var callback = expectAsync(() {});
-      var excesscallback = expectAsync(() {});
-      return new Future.sync(() {
-        excesscallback();
-        excesscallback();
-        callback();
-      });
-    });
-    test("fail2", () {
-      return new Future.sync(() {
-        fail('failure');
-      });
-    });
-    test('foo5', () {});
-  }, [
-    {'result': 'pass'},
-    {
-      'result': 'fail',
-      'message': 'Callback called more times than expected (1).'
-    },
-    {'result': 'fail', 'message': 'Expected: <false>\n  Actual: <true>\n'},
-    {
-      'result': 'fail',
-      'message': 'Callback called more times than expected (1).'
-    },
-    {'result': 'fail', 'message': 'failure'},
-    {'result': 'pass'}
-  ]);
-}