Add an AnalysisOptionsProvider to analyzer

pkg/analyzer/test/source/analysis_options_provider_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.
+
+library test.source.analysis_options_provider;
+
+import 'package:analyzer/file_system/memory_file_system.dart';
+import 'package:analyzer/source/analysis_options_provider.dart';
+import 'package:unittest/unittest.dart';
+import 'package:yaml/yaml.dart';
+
+main() {
+  groupSep = ' | ';
+  group('AnalysisOptionsProvider', () {
+    setUp(() {
+      buildResourceProvider();
+    });
+    tearDown(() {
+      clearResourceProvider();
+    });
+    test('test_simple', () {
+      var optionsProvider = new AnalysisOptionsProvider();
+      Map<String, YamlNode> options =
+          optionsProvider.getOptions(resourceProvider.getFolder('/'));
+      expect(options.length, equals(1));
+      expect(options['analyzer'], isNotNull);
+      YamlMap analyzer = options['analyzer'];
+      expect(analyzer.length, equals(1));
+      expect(analyzer['ignore'], isNotNull);
+      YamlList ignore = analyzer['ignore'];
+      expect(ignore.length, equals(2));
+      expect(ignore[0], equals('ignoreme.dart'));
+      expect(ignore[1], equals('sdk_ext/**'));
+    });
+    test('test_doesnotexist', () {
+      var optionsProvider = new AnalysisOptionsProvider();
+      Map<String, YamlNode> options =
+          optionsProvider.getOptions(resourceProvider.getFolder('/empty'));
+      expect(options.length, equals(0));
+    });
+  });
+}
+
+MemoryResourceProvider resourceProvider;
+
+buildResourceProvider() {
+  resourceProvider = new MemoryResourceProvider();
+  resourceProvider.newFolder('/empty');
+  resourceProvider.newFolder('/tmp');
+  resourceProvider.newFile('/.analysis_options', r'''
+analyzer:
+  ignore:

[pquitslund, 2015/07/17 20:31:31]

FWIW: I think there was some leaning towards `exclude` so that we could support
the include/exclude dichotomy.

[Cutch, 2015/07/17 20:33:48]

Acknowledged.

+    - ignoreme.dart
+    - 'sdk_ext/**'
+''');
+}
+
+clearResourceProvider() {
+  resourceProvider = null;
+}
+
+emptyResourceProvider() {
+  resourceProvider = new MemoryResourceProvider();
+}