Add a skip parameter to expect().

lib/src/backend/invoker.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:async';
 
 import 'package:stack_trace/stack_trace.dart';
 
 import '../frontend/expect.dart';
 import '../runner/load_suite.dart';
@@ skipping 213 matching lines @@
     _timeoutTimer = _invokerZone.createTimer(timeout, () {
       _outstandingCallbackZones.last.run(() {
         if (liveTest.isComplete) return;
         _handleError(
             new TimeoutException(
                 "Test timed out after ${niceDuration(timeout)}.", timeout));
       });
     });
   }
 
+  /// Marks the current test as skipped.
+  ///
+  /// If passed, [message] is emitted as a skip message.
+  ///
+  /// Note that this *does not* mark the test as complete. That is, it sets
+  /// the result to [Result.skipped], but doesn't change the state.
+  void skip([String message]) {
+    if (liveTest.state.shouldBeDone) {
+      // Set the state explicitly so we don't get an extra error about the test
+      // failing after being complete.
+      _controller.setState(const State(Status.complete, Result.error));
+      throw "This test was marked as skipped after it had already completed. "
+               "Make sure to use\n"
+            "[expectAsync] or the [completes] matcher when testing async code.";
+    }
+
+    if (message != null) _controller.message(new Message.skip(message));
+    // TODO: error if the test is already complete.
+    _controller.setState(const State(Status.pending, Result.skipped));
+  }
+
   /// Notifies the invoker of an asynchronous error.
   void _handleError(error, [StackTrace stackTrace]) {
     if (stackTrace == null) stackTrace = new Chain.current();
 
     // Store this here because it'll change when we set the state below.
     var shouldBeDone = liveTest.state.shouldBeDone;
 
     if (error is! TestFailure) {
       _controller.setState(const State(Status.complete, Result.error));
     } else if (liveTest.state.result != Result.error) {
@@ skipping 58 matching lines @@
         _counterKey: outstandingCallbacksForBody,
         _closableKey: true
       },
           zoneSpecification: new ZoneSpecification(
               print: (self, parent, zone, line) =>
                   _controller.message(new Message.print(line))),
           onError: _handleError);
     });
   }
 }