MemoryResourceProvider.getFolder() should not create the folder.

pkg/analysis_server/test/single_context_manager_test.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.
 
 library test.analysis_server.src.single_context_manager;
 
 import 'dart:core';
 
 import 'package:analysis_server/src/single_context_manager.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
@@ skipping 56 matching lines @@
     DartSdkManager sdkManager =
         new DartSdkManager('', false, (_) => new MockSdk());
     manager = new SingleContextManager(resourceProvider, sdkManager,
         (_) => packageResolver, analysisFilesGlobs, new AnalysisOptionsImpl());
     callbacks = new TestContextManagerCallbacks(resourceProvider);
     manager.callbacks = callbacks;
   }
 
   void test_isIgnored_false() {
     String project = '/project';
+    resourceProvider.newFolder(project);
     manager.setRoots(<String>[project], <String>[], <String, String>{});
     expect(manager.isIgnored('$project/file.dart'), isFalse);
   }
 
   void test_isIgnored_true_inDotFolder() {
     String project = '/project';
+    resourceProvider.newFolder(project);
     manager.setRoots(<String>[project], <String>[], <String, String>{});
     expect(manager.isIgnored('$project/foo/.bar/file.dart'), isTrue);
   }
 
   void test_isIgnored_true_inExcludedPath() {
     String project = '/project';
     String excludedPath = '/project/excluded';
+    resourceProvider.newFolder(project);
     manager.setRoots(
         <String>[project], <String>[excludedPath], <String, String>{});
     expect(manager.isIgnored('$excludedPath/file.dart'), isTrue);
   }
 
   void test_isIgnored_true_notInRoot() {
     String root1 = '/context/root1';
     String root2 = '/context/root2';
+    resourceProvider.newFolder(root1);
+    resourceProvider.newFolder(root2);
     manager.setRoots(<String>[root1, root2], <String>[], <String, String>{});
     expect(manager.isIgnored('$context/root3/file.dart'), isTrue);
   }
 
   void test_isInAnalysisRoot_false_inExcludedPath() {
     String project = '/project';
     String excludedPath = '/project/excluded';
+    resourceProvider.newFolder(project);
     manager.setRoots(
         <String>[project], <String>[excludedPath], <String, String>{});
     expect(manager.isInAnalysisRoot('$excludedPath/file.dart'), isFalse);
   }
 
   void test_isInAnalysisRoot_false_notInRoot() {
     String root1 = '/context/root1';
     String root2 = '/context/root2';
+    resourceProvider.newFolder(root1);
+    resourceProvider.newFolder(root2);
     manager.setRoots(<String>[root1, root2], <String>[], <String, String>{});
     expect(manager.isInAnalysisRoot('$context/root3/file.dart'), isFalse);
   }
 
   void test_isInAnalysisRoot_true() {
     String project = '/project';
+    resourceProvider.newFolder(project);
     manager.setRoots(<String>[project], <String>[], <String, String>{});
     expect(manager.isInAnalysisRoot('$project/file.dart'), isTrue);
   }
 
   void test_refresh() {
     String project = '/project';
     String file1 = '$project/file1.dart';
     String file2 = '$project/file2.dart';
     // create files
     resourceProvider.newFile(file1, '');
@@ skipping 235 matching lines @@
     String project = '/.pub/project';
     String fileA = '$project/foo.dart';
     resourceProvider.newFile(fileA, '');
     manager.setRoots(<String>[project], <String>[], <String, String>{});
     callbacks.assertContextPaths([project]);
     callbacks.assertContextFiles(project, [fileA]);
   }
 
   test_watch_addFile() async {
     String project = '/project';
+    resourceProvider.newFolder(project);
     manager.setRoots(<String>[project], <String>[], <String, String>{});
     // empty folder initially
     callbacks.assertContextFiles(project, []);
     // add file
     String file = '$project/foo.dart';
     resourceProvider.newFile(file, 'contents');
     // the file was added
     await pumpEventQueue();
     callbacks.assertContextFiles(project, [file]);
   }
 
   test_watch_addFile_afterChangingRoots() async {
     String contextPath = '/context';
     String root1 = '$contextPath/root1';
     String root2 = '$contextPath/root2';
     String file1 = '$root1/file1.dart';
     String file2 = '$root2/file2.dart';
+    resourceProvider.newFolder(root1);
+    resourceProvider.newFolder(root2);
     manager.setRoots(<String>[root1], <String>[], <String, String>{});
     manager.setRoots(<String>[root2], <String>[], <String, String>{});
     manager.setRoots(<String>[root1, root2], <String>[], <String, String>{});
     manager.setRoots(<String>[root2], <String>[], <String, String>{});
     // empty folder initially
     callbacks.assertContextFiles(root2, []);
     // add files
     resourceProvider.newFile(file1, '');
     resourceProvider.newFile(file2, '');
     // the file was added
@@ skipping 51 matching lines @@
     resourceProvider.newFile(fileA, '');
     manager.setRoots(<String>[project], <String>[], <String, String>{});
     callbacks.assertContextPaths([project]);
     callbacks.assertContextFiles(project, [fileA]);
     resourceProvider.newFile(fileB, '');
     await pumpEventQueue();
     callbacks.assertContextPaths([project]);
     callbacks.assertContextFiles(project, [fileA]);
   }
 
-  test_watch_addFileInSubfolder() async {
+  test_watch_addFileInSubFolder() async {
     String project = '/project';
+    resourceProvider.newFolder(project);
     manager.setRoots(<String>[project], <String>[], <String, String>{});
     // empty folder initially
     callbacks.assertContextFiles(project, []);
     // add file in subfolder
     String file = '$project/foo/bar.dart';
     resourceProvider.newFile(file, 'contents');
     // the file was added
     await pumpEventQueue();
     callbacks.assertContextFiles(project, [file]);
   }
@@ skipping 54 matching lines @@
     manager.processPlugins(plugins);
   }
 }
 
 class TestUriResolver extends UriResolver {
   @override
   Source resolveAbsolute(Uri uri, [Uri actualUri]) {
     return null;
   }
 }