Add on_os and on_platform fields.

lib/src/runner/configuration.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 'dart:io';
 
 import 'package:boolean_selector/boolean_selector.dart';
 import 'package:collection/collection.dart';
 import 'package:glob/glob.dart';
 import 'package:path/path.dart' as p;
@@ skipping 121 matching lines @@
   final Set<String> addTags;
 
   /// The global test metadata derived from this configuration.
   Metadata get metadata => new Metadata(
       timeout: timeout,
       verboseTrace: verboseTrace,
       skip: skip,
       skipReason: skipReason,
       testOn: testOn,
       tags: addTags,
-      forTag: mapMap(tags, value: (_, config) => config.metadata));
+      forTag: mapMap(tags, value: (_, config) => config.metadata),
+      onPlatform: mapMap(onPlatform, value: (_, config) => config.metadata));
 
   /// The set of tags that have been declaredin any way in this configuration.
   Set<String> get knownTags {
     if (_knownTags != null) return _knownTags;
 
     var known = includeTags.variables.toSet()
       ..addAll(excludeTags.variables)
       ..addAll(addTags);
     tags.forEach((selector, config) {
       known.addAll(selector.variables);
       known.addAll(config.knownTags);
     });
 
     _knownTags = new UnmodifiableSetView(known);
     return _knownTags;
   }
   Set<String> _knownTags;
 
+  /// Configuration for particular platforms.
+  ///
+  /// The keys are platform selectors, and the values are configurations for
+  /// those platforms. These configuration should only contain test-level
+  /// configuration fields, but that isn't enforced.
+  final Map<PlatformSelector, Configuration> onPlatform;
+
   /// Parses the configuration from [args].
   ///
   /// Throws a [FormatException] if [args] are invalid.
   factory Configuration.parse(List<String> arguments) => args.parse(arguments);
 
   /// Loads the configuration from [path].
   ///
   /// Throws an [IOException] if [path] does not exist or cannot be read. Throws
   /// a [FormatException] if its contents are invalid.
   factory Configuration.load(String path) => load(path);
@@ skipping 13 matching lines @@
           int pubServePort,
           int concurrency,
           Timeout timeout,
           this.pattern,
           Iterable<TestPlatform> platforms,
           Iterable<String> paths,
           Glob filename,
           BooleanSelector includeTags,
           BooleanSelector excludeTags,
           Iterable addTags,
-          Map<BooleanSelector, Configuration> tags})
+          Map<BooleanSelector, Configuration> tags,
+          Map<PlatformSelector, Configuration> onPlatform})
       : _help = help,
         _version = version,
         _verboseTrace = verboseTrace,
         _jsTrace = jsTrace,
         _skip = skip,
         testOn = testOn ?? PlatformSelector.all,
         _pauseAfterLoad = pauseAfterLoad,
         _color = color,
         _packageRoot = packageRoot,
         _reporter = reporter,
         pubServeUrl = pubServePort == null
             ? null
             : Uri.parse("http://localhost:$pubServePort"),
         _concurrency = concurrency,
         timeout = (pauseAfterLoad ?? false)
             ? Timeout.none
             : (timeout == null ? new Timeout.factor(1) : timeout),
         _platforms = _list(platforms),
         _paths = _list(paths),
         _filename = filename,
         includeTags = includeTags ?? BooleanSelector.all,
         excludeTags = excludeTags ?? BooleanSelector.none,
         addTags = addTags?.toSet() ?? new Set(),
-        tags = tags == null ? const {} : new Map.unmodifiable(tags) {
+        tags = tags == null ? const {} : new Map.unmodifiable(tags),
+        onPlatform = onPlatform == null
+            ? const {}
+            : new Map.unmodifiable(onPlatform) {
     if (_filename != null && _filename.context.style != p.style) {
       throw new ArgumentError(
           "filename's context must match the current operating system, was "
               "${_filename.context.style}.");
     }
   }
 
   /// Returns a [input] as a list or `null`.
   ///
   /// If [input] is `null` or empty, this returns `null`. Otherwise, it returns
@@ skipping 27 matching lines @@
         concurrency: other._concurrency ?? _concurrency,
         timeout: timeout.merge(other.timeout),
         pattern: other.pattern ?? pattern,
         platforms: other._platforms ?? _platforms,
         paths: other._paths ?? _paths,
         filename: other._filename ?? _filename,
         includeTags: includeTags.intersection(other.includeTags),
         excludeTags: excludeTags.union(other.excludeTags),
         addTags: other.addTags.union(addTags),
         tags: mergeMaps(tags, other.tags,
+            value: (config1, config2) => config1.merge(config2)),
+        onPlatform: mergeMaps(onPlatform, other.onPlatform,
             value: (config1, config2) => config1.merge(config2)));
   }
 }