Extract 'DartUnitHighlightsComputer' tests into a separate file.

pkg/analysis_server/test/analysis_notification_navigation_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.
 
 library test.domain.analysis.notification.navigation;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
 import 'package:unittest/unittest.dart';
 
 import 'analysis_abstract.dart';
 import 'reflective_tests.dart';
 
 
 main() {
   group('notification.navigation', () {
-    runReflectiveTests(AnalysisNotificationNavigationTest);
+    runReflectiveTests(_AnalysisNotificationNavigationTest);

[Brian Wilkerson, 2014/06/18 16:28:37]

Is there any reason to make any test code private? Seems pointless, but I don't
have a problem with it.

[scheglov, 2014/06/18 16:34:47]

I do it by the same reasons as for the all code - to show that this code is not
used outside of its library.
I don't have a strong preference, it just makes the code slightly easier to
understand.

   });
 }
 
 
 @ReflectiveTestCase()
-class AnalysisNotificationNavigationTest extends AbstractAnalysisTest {
+class _AnalysisNotificationNavigationTest extends AbstractAnalysisTest {
   List<_NavigationRegion> regions;
   _NavigationRegion testRegion;
   List<_NavigationTarget> testTargets;
 
   @override
   void setUp() {
     super.setUp();
     createProject();
   }
 
@@ skipping 417 matching lines @@
 }
 
 
 class _NavigationTarget {
   final String file;
   final int offset;
   final int length;
 
   _NavigationTarget(this.file, this.offset, this.length);
 }