Support tag configuration.

test/backend/metadata_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/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';
 
@@ skipping 26 matching lines @@
       expect(merged.tags, unorderedEquals(["a", "b", "c"]));
     });
 
     test("serializes and deserializes tags", () {
       var metadata = new Metadata(tags: ["a", "b"]).serialize();
       expect(new Metadata.deserialize(metadata).tags,
           unorderedEquals(['a', 'b']));
     });
   });
 
+  group("constructor", () {
+    test("returns the normal metadata if there's no forTag", () {
+      var metadata = new Metadata(verboseTrace: true, tags: ['foo', 'bar']);
+      expect(metadata.verboseTrace, isTrue);
+      expect(metadata.tags, equals(['foo', 'bar']));
+    });
+
+    test("returns the normal metadata if there's no tags", () {
+      var metadata = new Metadata(verboseTrace: true,
+          forTag: {'foo': new Metadata(skip: true)});
+      expect(metadata.verboseTrace, isTrue);
+      expect(metadata.skip, isFalse);
+      expect(metadata.forTag, contains('foo'));
+      expect(metadata.forTag['foo'].skip, isTrue);
+    });
+
+    test("returns the normal metadata if forTag doesn't match tags", () {
+      var metadata = new Metadata(
+          verboseTrace: true,
+          tags: ['bar', 'baz'],
+          forTag: {'foo': new Metadata(skip: true)});
+
+      expect(metadata.verboseTrace, isTrue);
+      expect(metadata.skip, isFalse);
+      expect(metadata.tags, ['bar', 'baz']);
+      expect(metadata.forTag, contains('foo'));
+      expect(metadata.forTag['foo'].skip, isTrue);
+    });
+
+    test("resolves forTags that match tags", () {
+      var metadata = new Metadata(
+          verboseTrace: true,
+          tags: ['foo', 'bar', 'baz'],
+          forTag: {
+            'foo': new Metadata(skip: true),
+            'baz': new Metadata(timeout: Timeout.none),
+            'qux': new Metadata(skipReason: "blah")
+          });
+
+      expect(metadata.verboseTrace, isTrue);
+      expect(metadata.skip, isTrue);
+      expect(metadata.skipReason, isNull);
+      expect(metadata.timeout, equals(Timeout.none));
+      expect(metadata.tags, equals(['foo', 'bar', 'baz']));
+      expect(metadata.forTag.keys, equals(['qux']));
+    });
+
+    test("base metadata takes precedence over forTags", () {
+      var metadata = new Metadata(
+          verboseTrace: true,
+          tags: ['foo'],
+          forTag: {'foo': new Metadata(verboseTrace: false)});
+
+      expect(metadata.verboseTrace, isTrue);
+    });
+  });
+
   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);
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       }, throwsArgumentError);
     });
 
     test("refuses multiple Skips", () {
       expect(() {
         new Metadata.parse(onPlatform: {"chrome": [new Skip(), new Skip()]});
       }, throwsArgumentError);
     });
   });
 }