Add a platform plugin infrastructure.

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 'dart:async';
 
 import 'package:test/src/backend/group.dart';
 import 'package:test/src/backend/state.dart';
 import 'package:test/src/runner/engine.dart';
+import 'package:test/src/runner/plugin/environment.dart';
 import 'package:test/src/runner/runner_suite.dart';
-import 'package:test/src/runner/vm/environment.dart';
 import 'package:test/test.dart';
 
 import '../utils.dart';
 
 void main() {
   test("runs each test in each suite in order", () async {
     var testsRun = 0;
     var tests = declare(() {
       for (var i = 0; i < 4; i++) {
         test("test ${i + 1}", expectAsync(() {
           expect(testsRun, equals(i));
           testsRun++;
         }, max: 1));
       }
     });
 
     var engine = new Engine.withSuites([
-      new RunnerSuite(const VMEnvironment(), new Group.root(tests.take(2))),
-      new RunnerSuite(const VMEnvironment(), new Group.root(tests.skip(2)))
+      new RunnerSuite(const PluginEnvironment(), new Group.root(tests.take(2))),
+      new RunnerSuite(const PluginEnvironment(), new Group.root(tests.skip(2)))
     ]);
 
     await engine.run();
     expect(testsRun, equals(4));
   });
 
   test("runs tests in a suite added after run() was called", () {
     var testsRun = 0;
     var tests = declare(() {
       for (var i = 0; i < 4; i++) {
         test("test ${i + 1}", expectAsync(() {
           expect(testsRun, equals(i));
           testsRun++;
         }, max: 1));
       }
     });
 
     var engine = new Engine();
     expect(engine.run().then((_) {
       expect(testsRun, equals(4));
     }), completes);
 
     engine.suiteSink.add(
-        new RunnerSuite(const VMEnvironment(), new Group.root(tests)));
+        new RunnerSuite(const PluginEnvironment(), 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 = declareEngine(() {
       for (var i = 0; i < 3; i++) {
         test("test ${i + 1}", expectAsync(() => testsRun++, max: 1));
       }
@@ skipping 93 matching lines @@
       await engine.run();
       expect(bodyRun, isFalse);
     });
 
     test("exposes a LiveTest that emits the correct states", () {
       var tests = declare(() {
         test("test", () {}, skip: true);
       });
 
       var engine = new Engine.withSuites([
-        new RunnerSuite(const VMEnvironment(), new Group.root(tests))
+        new RunnerSuite(const PluginEnvironment(), 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();
     });
   });
 }