Add test- and group-level support for skipping tests.

test/runner/engine_test.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 'package:test/src/backend/declarer.dart';
 import 'package:test/src/backend/state.dart';
 import 'package:test/src/backend/suite.dart';
 import 'package:test/src/runner/engine.dart';
 import 'package:test/test.dart';
 
@@ skipping 66 matching lines @@
 
     var engine = new Engine([new Suite(declarer.tests)]);
     expect(engine.run(), completion(isFalse));
   });
 
   test(".run() may not be called more than once", () {
     var engine = new Engine([]);
     expect(engine.run(), completes);
     expect(() => engine.run(), throwsStateError);
   });
+
+  group("for a skipped test", () {
+    test("doesn't run the test's body", () {
+      var bodyRun = false;
+      declarer.test("test", () => bodyRun = true, skip: true);
+
+      var engine = new Engine([new Suite(declarer.tests)]);
+      return engine.run().then((_) {
+        expect(bodyRun, isFalse);
+      });
+    });
+
+    test("exposes a LiveTest that emits the correct states", () {
+      declarer.test("test", () {}, skip: true);
+
+      var engine = new Engine([new Suite(declarer.tests)]);
+      var liveTest = engine.liveTests.single;
+      expect(liveTest.test, equals(declarer.tests.single));
+
+      var first = true;
+      liveTest.onStateChange.listen(expectAsync((state) {
+        expect(state, equals(first
+            ? const State(Status.running, Result.success)
+            : const State(Status.complete, Result.success)));
+        first = false;
+      }, count: 2));
+
+      expect(liveTest.onComplete, completes);
+
+      return engine.run();
+    });
+  });
 }