feature: tag tests; choose tags on command line

lib/src/runner/parse_metadata.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.
 
 library test.runner.parse_metadata;
 
 import 'dart:io';
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 37 matching lines @@
       return directive.prefix.name;
     }).where((prefix) => prefix != null).toSet();
   }
 
   /// Parses the metadata.
   Metadata parse() {
     var timeout;
     var testOn;
     var skip;
     var onPlatform;
+    var tags;
 
     for (var annotation in _annotations) {
       var pair = _resolveConstructor(
           annotation.name, annotation.constructorName);
       var name = pair.first;
       var constructorName = pair.last;
 
       if (name == 'TestOn') {
         _assertSingle(testOn, 'TestOn', annotation);
         testOn = _parseTestOn(annotation, constructorName);
       } else if (name == 'Timeout') {
         _assertSingle(timeout, 'Timeout', annotation);
         timeout = _parseTimeout(annotation, constructorName);
       } else if (name == 'Skip') {
         _assertSingle(skip, 'Skip', annotation);
         skip = _parseSkip(annotation, constructorName);
       } else if (name == 'OnPlatform') {
         _assertSingle(onPlatform, 'OnPlatform', annotation);
         onPlatform = _parseOnPlatform(annotation, constructorName);
+      } else if (name == 'Tags') {
+        _assertSingle(tags, 'Tags', annotation);
+        tags = _parseTags(annotation, constructorName);
       }
     }
 
     return new Metadata(
         testOn: testOn,
         timeout: timeout,
         skip: skip != null,
         skipReason: skip is String ? skip : null,
-        onPlatform: onPlatform);
+        onPlatform: onPlatform,
+        tags: tags);
   }
 
   /// Parses a `@TestOn` annotation.
   ///
   /// [annotation] is the annotation. [constructorName] is the name of the named
   /// constructor for the annotation, if any.
   PlatformSelector _parseTestOn(Annotation annotation, String constructorName) {
     _assertConstructorName(constructorName, 'TestOn', annotation);
     _assertArguments(annotation.arguments, 'TestOn', annotation, positional: 1);
     var literal = _parseString(annotation.arguments.arguments.first);
@@ skipping 60 matching lines @@
   /// Returns either `true` or a reason string.
   _parseSkipConstructor(InstanceCreationExpression constructor) {
     _parseConstructor(constructor, 'Skip');
     _assertArguments(constructor.argumentList, 'Skip', constructor,
         optional: 1);
 
     var args = constructor.argumentList.arguments;
     return args.isEmpty ? true : _parseString(args.first).stringValue;
   }
 
+  /// Parses a `@Tags` annotation.
+  ///
+  /// [annotation] is the annotation. [constructorName] is the name of the named
+  /// constructor for the annotation, if any.
+  Set<String> _parseTags(Annotation annotation, String constructorName) {
+    _assertConstructorName(constructorName, 'Tags', annotation);
+    _assertArguments(annotation.arguments, 'Tags', annotation, positional: 1);
+    var arg = annotation.arguments.arguments.first;
+    if (arg is ListLiteral) {
+      var tagExpressions = _parseList(arg);
+      return new Set<String>.from(
+          tagExpressions.map((tagExpr) => _parseString(tagExpr).stringValue));
+    } else if (arg is StringLiteral) {
+      return new Set<String>.from([_parseString(arg).stringValue]);
+    } else {
+      throw new SourceSpanFormatException(
+          'Only String or List literal allowed as @Tags argument',
+          _spanFor(arg));
+    }
+  }
+
   /// Parses an `@OnPlatform` annotation.
   ///
   /// [annotation] is the annotation. [constructorName] is the name of the named
   /// constructor for the annotation, if any.
   Map<PlatformSelector, Metadata> _parseOnPlatform(Annotation annotation,
       String constructorName) {
     _assertConstructorName(constructorName, 'OnPlatform', annotation);
     _assertArguments(annotation.arguments, 'OnPlatform', annotation,
         positional: 1);
 
@@ skipping 335 matching lines @@
       return fn();
     } on SourceSpanFormatException catch (error) {
       var file = new SourceFile(new File(_path).readAsStringSync(),
           url: p.toUri(_path));
       var span = contextualizeSpan(error.span, literal, file);
       if (span == null) rethrow;
       throw new SourceSpanFormatException(error.message, span);
     }
   }
 }