Pass actual TestPlatform and OperatingSystem values to Suite.

test/runner/loader_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.
 
 @TestOn("vm")
 
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
 import 'package:test/src/backend/state.dart';
@@ skipping 41 matching lines @@
       new File(p.join(_sandbox, 'a_test.dart')).writeAsStringSync(_tests);
       var suites = await _loader.loadFile(p.join(_sandbox, 'a_test.dart'))
           .toList();
       expect(suites, hasLength(1));
       var loadSuite = suites.first;
       suite = await loadSuite.getSuite();
     });
 
     test("returns a suite with the file path and platform", () {
       expect(suite.path, equals(p.join(_sandbox, 'a_test.dart')));
-      expect(suite.platform, equals('VM'));
+      expect(suite.platform, equals(TestPlatform.vm));
     });
 
     test("returns tests with the correct names and platforms", () {
       expect(suite.tests, hasLength(3));
       expect(suite.tests[0].name, equals("success"));
       expect(suite.tests[1].name, equals("failure"));
       expect(suite.tests[2].name, equals("error"));
     });
 
     test("can load and run a successful test", () {
@@ skipping 87 matching lines @@
 
     var liveTest = await loadSuite.tests.single.load(loadSuite);
     expect(liveTest.onPrint.first, completion(equals("print within test")));
     await liveTest.run();
     expectTestPassed(liveTest);
   });
 
   // TODO: Test load suites. Don't forget to test that prints in loaded files
   // are piped through the suite. Also for browser tests!
 }