pkg/unittest: support up to 6 arguments in expectAsync[Until]

pkg/unittest/test/unittest_expect_async_args_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 unittestTest;
+
+import 'dart:isolate';
+import 'dart:async';
+import 'package:unittest/unittest.dart';
+
+part 'unittest_test_utils.dart';
+
+var testFunction = (TestConfiguration testConfig) {
+  List<int> _getArgs([a = 0, b = 0, c = 0, d = 0, e = 0, f = 0]) {
+    testConfig.count++;
+    return [a, b, c, d, e, f];
+  }
+
+  test('expect async args', () {
+    expect(expectAsync(_getArgs)(), [0, 0, 0, 0, 0, 0]);
+    expect(expectAsync(_getArgs)(5), [5, 0, 0, 0, 0, 0]);
+    expect(expectAsync(_getArgs)(1, 2, 3, 4, 5, 6), [1, 2, 3, 4, 5, 6]);
+  });
+
+  test('invoked with too many args', () {
+    expectAsync(_getArgs)(1, 2, 3, 4, 5, 6, 7);
+  });
+
+  test('created with too many args', () {
+    expectAsync((a1, a2, a3, a4, a5, a6, a7) {
+      testConfig.count++;
+    })();
+  });
+};
+
+final expected = startsWith('1:0:2:3:3:::null:expect async args::'
+    'invoked with too many args:Test failed:');