Add an integration test for diagnostics.getDiagnostics.

pkg/analysis_server/test/integration/test_all.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.integration.all;
 
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'analysis/test_all.dart' as analysis_test_all;
 import 'completion/test_all.dart' as completion_test_all;
 import 'coverage_test.dart' as coverage_test;
+import 'diagnostic/test_all.dart' as diagnostic_test_all;
 import 'execution/test_all.dart' as execution_test_all;
 import 'search/test_all.dart' as search_test_all;
 import 'server/test_all.dart' as server_test_all;
 
 /**
  * Utility for manually running all integration tests.
  */
 main() {
   defineReflectiveSuite(() {
     analysis_test_all.main();
     completion_test_all.main();
+    diagnostic_test_all.main();
     execution_test_all.main();
     search_test_all.main();
     server_test_all.main();
 
     coverage_test.main();
   }, name: 'analysis_server_integration');
 }