Use ResourceProvider instead of specialized setRealRoot/setFakeRoot.

pkg/analyzer2dart/test/tree_shaker_test.dart

 // Copyright (c) 2014, 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 'package:analysis_testing/mock_sdk.dart';
+import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:unittest/unittest.dart';
 
 import '../lib/src/closed_world.dart';
 import '../lib/src/driver.dart';
 
 main() {
@@ skipping 71 matching lines @@
   foo(new A());
 }
 ''');
     helper.assertHasMethod('A.m1');
     helper.assertHasMethod('A.m2');
   });
 }
 
 class TreeShakerTestHelper {
   /**
+   * The name of the root file.
+   */
+  String rootFile = '/root.dart';
+
+  /**
    * ClosedWorld that resulted from tree shaking.
    */
   ClosedWorld world;
 
   /**
    * Functions contained in [world], indexed by name.
    */
   Map<String, FunctionDeclaration> functions = <String, FunctionDeclaration>{};
 
   /**
    * Methods contained in [world], indexed by className.methodName.
    */
   Map<String, MethodDeclaration> methods = <String, MethodDeclaration>{};
 
   /**
    * Classes instantiated in [world], indexed by name.
    */
   Map<String, ClassDeclaration> instantiatedClasses = <String,
       ClassDeclaration>{};
 
   /**
    * Create a TreeShakerTestHelper based on the given file contents.
    */
   TreeShakerTestHelper(String contents) {
+    MemoryResourceProvider provider = new MemoryResourceProvider();
     DartSdk sdk = new MockSdk();
-    Driver driver = new Driver(sdk);
-    Source rootSource = driver.setFakeRoot(contents);
+    Driver driver = new Driver(provider, sdk);
+    provider.newFile(rootFile, contents);
+    Source rootSource = driver.setRoot(rootFile);
     FunctionElement entryPoint = driver.resolveEntryPoint(rootSource);
     world = driver.computeWorld(entryPoint);
     world.executableElements.forEach(
         (ExecutableElement element, Declaration node) {
       if (element is FunctionElement) {
         FunctionDeclaration declaration = node as FunctionDeclaration;
         expect(declaration, isNotNull);
         expect(declaration.element, equals(element));
         functions[element.name] = declaration;
       } else if (element is MethodElement) {
@@ skipping 49 matching lines @@
   /**
    * Asserts that [world] doesn't contain a method with the given qualified
    * name.
    *
    * [qualifiedName] - the qualified name in form 'className.methodName'.
    */
   void assertNoMethod(String qualifiedName) {
     expect(methods, isNot(contains(qualifiedName)));
   }
 }