Add support for configuration presets.

lib/src/runner/configuration/load.dart

 // Copyright (c) 2016, 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:glob/glob.dart';
 import 'package:path/path.dart' as p;
 import 'package:source_span/source_span.dart';
 import 'package:yaml/yaml.dart';
 
 import '../../backend/operating_system.dart';
 import '../../backend/platform_selector.dart';
 import '../../backend/test_platform.dart';
 import '../../frontend/timeout.dart';
 import '../../utils.dart';
 import '../../util/io.dart';
 import '../configuration.dart';
 import 'values.dart';
 
 /// Loads configuration information from a YAML file at [path].
 ///
 /// Throws a [FormatException] if the configuration is invalid, and a
 /// [FileSystemException] if it can't be read.
 Configuration load(String path) {
   var source = new File(path).readAsStringSync();
   var document = loadYamlNode(source, sourceUrl: p.toUri(path));
 
-  if (document.value == null) return new Configuration();
+  if (document.value == null) return Configuration.empty;
 
   if (document is! Map) {
     throw new SourceSpanFormatException(
         "The configuration must be a YAML map.", document.span, source);
   }
 
   var loader = new _ConfigurationLoader(document, source);
   return loader.load();
 }
 
@@ skipping 27 matching lines @@
     if (skip is String) {
       skipReason = skip;
       skip = true;
     }
 
     var testOn = _parseValue("test_on",
         (value) => new PlatformSelector.parse(value));
 
     var timeout = _parseValue("timeout", (value) => new Timeout.parse(value));
 
-    var addTags = _getList("add_tags", (tagNode) {
-      _validate(tagNode, "Tags must be strings.", (value) => value is String);
-      _validate(
-          tagNode,
-          "Invalid tag. Tags must be (optionally hyphenated) Dart identifiers.",
-          (value) => value.contains(anchoredHyphenatedIdentifier));
-      return tagNode.value;
-    });
+    var addTags = _getList("add_tags",
+        (tagNode) => _parseIdentifierLike(tagNode, "Tag name"));
 
     var tags = _getMap("tags",
         key: (keyNode) => _parseNode(keyNode, "tags key",
             (value) => new BooleanSelector.parse(value)),
         value: (valueNode) =>
             _nestedConfig(valueNode, "tag value", runnerConfig: false));
 
     var onPlatform = _getMap("on_platform",
         key: (keyNode) => _parseNode(keyNode, "on_platform key",
             (value) => new PlatformSelector.parse(value)),
         value: (valueNode) =>
             _nestedConfig(valueNode, "on_platform value", runnerConfig: false));
 
     var onOS = _getMap("on_os", key: (keyNode) {
       _validate(keyNode, "on_os key must be a string.",
           (value) => value is String);
 
       var os = OperatingSystem.find(keyNode.value);
       if (os != null) return os;
 
       throw new SourceSpanFormatException(
           'Invalid on_os key: No such operating system.',
           keyNode.span, _source);
     }, value: (valueNode) => _nestedConfig(valueNode, "on_os value"));
 
+    var presets = _getMap("presets",
+        key: (keyNode) => _parseIdentifierLike(keyNode, "presets key"),
+        value: (valueNode) => _nestedConfig(valueNode, "presets value"));
+
     var config = new Configuration(
         verboseTrace: verboseTrace,
         jsTrace: jsTrace,
         skip: skip,
         skipReason: skipReason,
         testOn: testOn,
         timeout: timeout,
         addTags: addTags,
         tags: tags,
-        onPlatform: onPlatform);
+        onPlatform: onPlatform,
+        presets: presets);
 
     var osConfig = onOS[currentOS];
     return osConfig == null ? config : config.merge(osConfig);
   }
 
   /// Loads runner configuration (but not test configuration).
   ///
   /// If [_runnerConfig] is `false`, this will error if there are any
   /// runner-level configuration fields.
   Configuration _loadRunnerConfig() {
     if (!_runnerConfig) {
       _disallow("reporter");
       _disallow("pub_serve");
       _disallow("concurrency");
       _disallow("platforms");
       _disallow("paths");
       _disallow("filename");
-      return new Configuration();
+      _disallow("add_presets");
+      return Configuration.empty;
     }
 
     var reporter = _getString("reporter");
     if (reporter != null && !allReporters.contains(reporter)) {
       _error('Unknown reporter "$reporter".', "reporter");
     }
 
     var pubServePort = _getInt("pub_serve");
     var concurrency = _getInt("concurrency");
 
@@ skipping 10 matching lines @@
 
     var paths = _getList("paths", (pathNode) {
       _validate(pathNode, "Paths must be strings.", (value) => value is String);
       _validate(pathNode, "Paths must be relative.", p.url.isRelative);
 
       return _parseNode(pathNode, "path", p.fromUri);
     });
 
     var filename = _parseValue("filename", (value) => new Glob(value));
 
+    var chosenPresets = _getList("add_presets",
+        (presetNode) => _parseIdentifierLike(presetNode, "Preset name"));
+
     return new Configuration(
         reporter: reporter,
         pubServePort: pubServePort,
         concurrency: concurrency,
         platforms: platforms,
         paths: paths,
-        filename: filename);
+        filename: filename,
+        chosenPresets: chosenPresets);
   }
 
   /// Throws an exception with [message] if [test] returns `false` when passed
   /// [node]'s value.
   void _validate(YamlNode node, String message, bool test(value)) {
     if (test(node.value)) return;
     throw new SourceSpanFormatException(message, node.span, _source);
   }
 
   /// Returns the value of the node at [field].
@@ skipping 60 matching lines @@
           (value) => value is String);
 
       return valueNode.value;
     };
 
     return mapMap(node.nodes,
         key: (keyNode, _) => key(keyNode),
         value: (_, valueNode) => value(valueNode));
   }
 
+  String _parseIdentifierLike(YamlNode node, String name) {
+    _validate(node, "$name must be a string.", (value) => value is String);
+    _validate(
+        node,
+        "$name must be an (optionally hyphenated) Dart identifier.",
+        (value) => value.contains(anchoredHyphenatedIdentifier));
+    return node.value;
+  }
+
   /// Asserts that [node] is a string, passes its value to [parse], and returns
   /// the result.
   ///
   /// If [parse] throws a [FormatException], it's wrapped to include [node]'s
   /// span.
   _parseNode(YamlNode node, String name, parse(String value)) {
     _validate(node, "$name must be a string.", (value) => value is String);
 
     try {
       return parse(node.value);
@@ skipping 14 matching lines @@
     return _parseNode(node, field, parse);
   }
 
   /// Parses a nested configuration document.
   ///
   /// [name] is the name of the field, which is used for error-handling.
   /// [runnerConfig] controls whether runner configuration is allowed in the
   /// nested configuration. It defaults to [_runnerConfig].
   Configuration _nestedConfig(YamlNode node, String name,
       {bool runnerConfig}) {
-    if (node == null || node.value == null) return new Configuration();
+    if (node == null || node.value == null) return Configuration.empty;
 
     _validate(node, "$name must be a map.", (value) => value is Map);
     var loader = new _ConfigurationLoader(node, _source,
         runnerConfig: runnerConfig ?? _runnerConfig);
     return loader.load();
   }
 
   /// Throws an error if a field named [field] exists at this level.
   void _disallow(String field) {
     if (!_document.containsKey(field)) return;
     _error("$field isn't supported here.", field);
   }
 
   /// Throws a [SourceSpanFormatException] with [message] about [field].
   void _error(String message, String field) {
     throw new SourceSpanFormatException(
         message, _document.nodes[field].span, _source);
   }
 }