Add support for setUpAll and tearDownAll.

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/group.dart';
 import 'package:test/src/backend/state.dart';
 import 'package:test/src/backend/test.dart';
 import 'package:test/src/runner/engine.dart';
 import 'package:test/src/runner/runner_suite.dart';
 import 'package:test/src/runner/vm/environment.dart';
@@ skipping 39 matching lines @@
     }), completes);
 
     engine.suiteSink.add(
         new RunnerSuite(const VMEnvironment(), new Group.root(tests)));
     engine.suiteSink.close();
   });
 
   test("emits each test before it starts running and after the previous test "
       "finished", () {
     var testsRun = 0;
-    var engine = withTests(declare(() {
+    var engine = declareEngine(() {
       for (var i = 0; i < 3; i++) {
         test("test ${i + 1}", expectAsync(() => testsRun++, max: 1));
       }
-    }));
+    });
 
     engine.onTestStarted.listen(expectAsync((liveTest) {
       // [testsRun] should be one less than the test currently running.
       expect(liveTest.test.name, equals("test ${testsRun + 1}"));
 
       // [Engine.onTestStarted] is guaranteed to fire before the first
       // [LiveTest.onStateChange].
       expect(liveTest.onStateChange.first,
           completion(equals(const State(Status.running, Result.success))));
     }, count: 3, max: 3));
 
     return engine.run();
   });
 
   test(".run() returns true if every test passes", () {
-    var engine = withTests(declare(() {
+    var engine = declareEngine(() {
       for (var i = 0; i < 2; i++) {
         test("test ${i + 1}", () {});
       }
-    }));
+    });
 
     expect(engine.run(), completion(isTrue));
   });
 
   test(".run() returns false if any test fails", () {
-    var engine = withTests(declare(() {
+    var engine = declareEngine(() {
       for (var i = 0; i < 2; i++) {
         test("test ${i + 1}", () {});
       }
       test("failure", () => throw new TestFailure("oh no"));
-    }));
+    });
 
     expect(engine.run(), completion(isFalse));
   });
 
   test(".run() returns false if any test errors", () {
-    var engine = withTests(declare(() {
+    var engine = declareEngine(() {
       for (var i = 0; i < 2; i++) {
         test("test ${i + 1}", () {});
       }
       test("failure", () => throw "oh no");
-    }));
+    });
 
     expect(engine.run(), completion(isFalse));
   });
 
   test(".run() may not be called more than once", () {
     var engine = new Engine.withSuites([]);
     expect(engine.run(), completes);
     expect(engine.run, throwsStateError);
   });
 
   group("for a skipped test", () {
     test("doesn't run the test's body", () async {
       var bodyRun = false;
-      var engine = withTests(declare(() {
+      var engine = declareEngine(() {
         test("test", () => bodyRun = true, skip: true);
-      }));
+      });
 
       await engine.run();
       expect(bodyRun, isFalse);
     });
 
     test("exposes a LiveTest that emits the correct states", () {
       var tests = declare(() {
         test("test", () {}, skip: true);
       });
 
-      var engine = withTests(tests);
+      var engine = new Engine.withSuites([
+        new RunnerSuite(const VMEnvironment(), new Group.root(tests))
+      ]);
 
       engine.onTestStarted.listen(expectAsync((liveTest) {
         expect(liveTest, same(engine.liveTests.single));
         expect(liveTest.test.name, equals(tests.single.name));
 
         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();
     });
   });
 }
-
-/// Returns an engine that will run [tests].
-Engine withTests(List<Test> tests) {
-  return new Engine.withSuites([
-    new RunnerSuite(const VMEnvironment(), new Group.root(tests))
-  ]);
-}