Add on_os and on_platform fields.

test/runner/test_on_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:scheduled_test/descriptor.dart' as d;
 import 'package:scheduled_test/scheduled_stream.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:test/src/util/io.dart';
 
 import '../io.dart';
 
 void main() {
   useSandbox();
 
   group("for suite", () {
     test("runs a test suite on a matching platform", () {
       _writeTestFile("vm_test.dart", suiteTestOn: "vm");
 
       var test = runTest(["vm_test.dart"]);
       test.stdout.expect(consumeThrough(contains("All tests passed!")));
       test.shouldExit(0);
     });
 
     test("doesn't run a test suite on a non-matching platform", () {
       _writeTestFile("vm_test.dart", suiteTestOn: "vm");
 
       var test = runTest(["--platform", "content-shell", "vm_test.dart"]);
       test.stdout.expect(consumeThrough(contains("No tests ran.")));
       test.shouldExit(0);
     }, tags: 'content-shell');
 
     test("runs a test suite on a matching operating system", () {
-      _writeTestFile("os_test.dart", suiteTestOn: currentOS.name);
+      _writeTestFile("os_test.dart", suiteTestOn: currentOS.identifier);
 
       var test = runTest(["os_test.dart"]);
       test.stdout.expect(consumeThrough(contains("All tests passed!")));
       test.shouldExit(0);
     });
 
     test("doesn't run a test suite on a non-matching operating system", () {
-      _writeTestFile("os_test.dart", suiteTestOn: _otherOS,
+      _writeTestFile("os_test.dart", suiteTestOn: otherOS,
           loadable: false);
 
       var test = runTest(["os_test.dart"]);
       test.stdout.expect(consumeThrough(contains("No tests ran.")));
       test.shouldExit(0);
     });
 
     test("only loads matching files when loading as a group", () {
       _writeTestFile("vm_test.dart", suiteTestOn: "vm");
       _writeTestFile("browser_test.dart",
           suiteTestOn: "browser", loadable: false);
-      _writeTestFile("this_os_test.dart", suiteTestOn: currentOS.name);
+      _writeTestFile("this_os_test.dart", suiteTestOn: currentOS.identifier);
       _writeTestFile("other_os_test.dart",
-          suiteTestOn: _otherOS, loadable: false);
+          suiteTestOn: otherOS, loadable: false);
 
       var test = runTest(["."]);
       test.stdout.expect(consumeThrough(contains("+2: All tests passed!")));
       test.shouldExit(0);
     });
   });
 
   group("for group", () {
     test("runs a VM group on the VM", () {
       _writeTestFile("vm_test.dart", groupTestOn: "vm");
@@ skipping 128 matching lines @@
   if (groupTestOn != null) {
     buffer.writeln("  }, testOn: '$groupTestOn');");
   } else {
     buffer.writeln("  });");
   }
 
   buffer.writeln("}");
 
   d.file(filename, buffer.toString()).create();
 }