Use ResourceProvider instead of specialized setRealRoot/setFakeRoot.

pkg/analyzer2dart/test/driver_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() {
+  MemoryResourceProvider provider;
   Driver driver;
   setUp(() {
+    provider = new MemoryResourceProvider();
     DartSdk sdk = new MockSdk();
-    driver = new Driver(sdk);
+    driver = new Driver(provider, sdk);
   });
 
-  test('setFakeRoot', () {
-    var contents = 'main() {}';
-    Source source = driver.setFakeRoot(contents);
-    expect(driver.context.getContents(source).data, equals(contents));
-  });
+  Source setFakeRoot(String contents) {
+    String path = '/root.dart';
+    provider.newFile(path, contents);
+    return driver.setRoot(path);
+  }
 
   test('resolveEntryPoint', () {
     String contents = 'main() {}';
-    FunctionElement element =
-        driver.resolveEntryPoint(driver.setFakeRoot(contents));
+    Source source = setFakeRoot(contents);
+    FunctionElement element = driver.resolveEntryPoint(source);
     expect(element.name, equals('main'));
   });
 
   test('computeWorld', () {
     String contents = '''
 main() {
   foo();
 }
 
 foo() {
 }
 
 bar() {
 }
 ''';
-    FunctionElement entryPoint =
-        driver.resolveEntryPoint(driver.setFakeRoot(contents));
+    Source source = setFakeRoot(contents);
+    FunctionElement entryPoint = driver.resolveEntryPoint(source);
     ClosedWorld world = driver.computeWorld(entryPoint);
     expect(world.executableElements, hasLength(2));
     CompilationUnitElement compilationUnit =
         entryPoint.getAncestor((e) => e is CompilationUnitElement);
     Map<String, FunctionElement> functions = {};
     for (FunctionElement functionElement in compilationUnit.functions) {
       functions[functionElement.name] = functionElement;
     }
     FunctionElement mainElement = functions['main'];
     expect(world.executableElements.keys, contains(mainElement));
     FunctionDeclaration mainAst = world.executableElements[mainElement];
     expect(mainAst.element, equals(mainElement));
     FunctionElement fooElement = functions['foo'];
     expect(world.executableElements.keys, contains(fooElement));
     FunctionDeclaration fooAst = world.executableElements[fooElement];
     expect(fooAst.element, equals(fooElement));
     FunctionElement barElement = functions['bar'];
     expect(
         world.executableElements.keys,
         isNot(contains(functions[barElement])));
   });
 }