Use an import prefix in the analysis server tests; this fixes some issues conflicting with the

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';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:analyzer/src/util/glob.dart';
 import 'package:linter/src/plugin/linter_plugin.dart';
-import 'package:path/path.dart';
+import 'package:path/path.dart' as path;
 import 'package:plugin/manager.dart';
 import 'package:plugin/plugin.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'context_manager_test.dart' show TestContextManagerCallbacks;
 import 'mocks.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SingleContextManagerTest);
   });
 }
 
 @reflectiveTest
 class SingleContextManagerTest {
   MemoryResourceProvider resourceProvider = new MemoryResourceProvider();
 
   TestUriResolver packageResolver;
   TestContextManagerCallbacks callbacks;
   SingleContextManager manager;
 
   List<Glob> get analysisFilesGlobs {
     List<String> patterns = <String>[
       '**/*.${AnalysisEngine.SUFFIX_DART}',
       '**/*.${AnalysisEngine.SUFFIX_HTML}',
     ];
     return patterns
-        .map((pattern) => new Glob(posix.separator, pattern))
+        .map((pattern) => new Glob(path.posix.separator, pattern))
         .toList();
   }
 
   String newFile(List<String> pathComponents, [String content = '']) {
-    String filePath = posix.joinAll(pathComponents);
+    String filePath = path.posix.joinAll(pathComponents);
     resourceProvider.newFile(filePath, content);
     return filePath;
   }
 
   String newFolder(List<String> pathComponents) {
-    String folderPath = posix.joinAll(pathComponents);
+    String folderPath = path.posix.joinAll(pathComponents);
     resourceProvider.newFolder(folderPath);
     return folderPath;
   }
 
   void setUp() {
     packageResolver = new TestUriResolver();
 
     _processRequiredPlugins();
     DartSdkManager sdkManager = new DartSdkManager('', false);
     manager = new SingleContextManager(resourceProvider, sdkManager,
@@ skipping 24 matching lines @@
         <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);
+    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);
+    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() {
@@ skipping 408 matching lines @@
     manager.processPlugins(plugins);
   }
 }
 
 class TestUriResolver extends UriResolver {
   @override
   Source resolveAbsolute(Uri uri, [Uri actualUri]) {
     return null;
   }
 }