Add an "onPlatform" parameter to test() and group().

test/backend/metadata_test.dart

Index: test/backend/metadata_test.dart
diff --git a/test/backend/metadata_test.dart b/test/backend/metadata_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9e696e5e02c6b8b1768987360661b49416e0c4b5
--- /dev/null
+++ b/test/backend/metadata_test.dart
@@ -0,0 +1,66 @@
+// 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/metadata.dart';
+import 'package:test/src/backend/test_platform.dart';
+import 'package:test/src/frontend/timeout.dart';
+import 'package:test/src/frontend/skip.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group("onPlatform", () {
+    test("parses a valid map", () {
+      var metadata = new Metadata.parse(onPlatform: {
+        "chrome": new Timeout.factor(2),
+        "vm": [new Skip(), new Timeout.factor(3)]
+      });
+
+      var key = metadata.onPlatform.keys.first;
+      expect(key.evaluate(TestPlatform.chrome), isTrue);
+      expect(key.evaluate(TestPlatform.vm), isFalse);
+      var value = metadata.onPlatform.values.first;
+      expect(value.timeout.scaleFactor, equals(2));
+
+
+      key = metadata.onPlatform.keys.last;
+      expect(key.evaluate(TestPlatform.vm), isTrue);
+      expect(key.evaluate(TestPlatform.chrome), isFalse);
+      value = metadata.onPlatform.values.last;
+      expect(value.skip, isTrue);
+      expect(value.timeout.scaleFactor, equals(3));
+    });
+
+    test("refuses an invalid value", () {
+      expect(() {
+        new Metadata.parse(onPlatform: {"chrome": new TestOn("chrome")});
+      }, throwsArgumentError);
+    });
+
+    test("refuses an invalid value in a list", () {
+      expect(() {
+        new Metadata.parse(onPlatform: {"chrome": [new TestOn("chrome")]});
+      }, throwsArgumentError);
+    });
+
+    test("refuses an invalid platform selector", () {
+      expect(() {
+        new Metadata.parse(onPlatform: {"invalid": new Skip()});
+      }, throwsFormatException);
+    });
+
+    test("refuses multiple Timeouts", () {
+      expect(() {
+        new Metadata.parse(onPlatform: {
+          "chrome": [new Timeout.factor(2), new Timeout.factor(3)]
+        });
+      }, throwsArgumentError);
+    });
+
+    test("refuses multiple Skips", () {
+      expect(() {
+        new Metadata.parse(onPlatform: {"chrome": [new Skip(), new Skip()]});
+      }, throwsArgumentError);
+    });
+  });
+}