More test clean-up

pkg/analyzer/test/src/task/dart_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 analyzer.test.src.task.dart_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 909 matching lines @@
 part 'part.dart';
 ''',
       '/part.dart': '''
 // no part of
 '''
     });
     _assertErrorsWithCodes([CompileTimeErrorCode.PART_OF_NON_PART]);
   }
 
   test_perform_invalidUri_part() {
+    String invalidUri = resourceProvider.pathContext.separator == '/'
+        ? '//////////'
+        : '\\\\\\\\\\\\';
     _performBuildTask({
       '/lib.dart': '''
 library lib;
-part '//////////';
+part '$invalidUri';
 '''
     });
     expect(libraryElement.parts, isEmpty);
   }
 
   test_perform_isLaunchable_inDefiningUnit() {
     _performBuildTask({
       '/lib.dart': '''
 library lib;
 main() {
@@ skipping 4711 matching lines @@
   /**
    * Fill [errorListener] with [result] errors in the current [task].
    */
   void _fillErrorListener(ResultDescriptor<List<AnalysisError>> result) {
     List<AnalysisError> errors = task.outputs[result] as List<AnalysisError>;
     expect(errors, isNotNull, reason: result.name);
     errorListener = new GatheringErrorListener();
     errorListener.addAll(errors);
   }
 }