Move diagnostics to `diagnostics` domain (#24931).

pkg/analysis_server/test/domain_diagnostic_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 test.domain.experimental;
+library test.domain.diagnostic;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/analysis_server.dart';
-import 'package:analysis_server/src/domain_experimental.dart';
+import 'package:analysis_server/src/domain_diagnostic.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/instrumentation/instrumentation.dart';
 import 'package:plugin/manager.dart';
 import 'package:unittest/unittest.dart';
 
 import 'mock_sdk.dart';
 import 'mocks.dart';
 import 'utils.dart';
 
 main() {
   AnalysisServer server;
-  ExperimentalDomainHandler handler;
+  DiagnosticDomainHandler handler;
   MemoryResourceProvider resourceProvider;
 
   initializeTestEnvironment();
 
   setUp(() {
     var serverChannel = new MockServerChannel();
     resourceProvider = new MemoryResourceProvider();
     ExtensionManager manager = new ExtensionManager();
     ServerPlugin serverPlugin = new ServerPlugin();
     manager.processPlugins([serverPlugin]);
     server = new AnalysisServer(
         serverChannel,
         resourceProvider,
         new MockPackageMapProvider(),
         null,
         serverPlugin,
         new AnalysisServerOptions(),
         new MockSdk(),
         InstrumentationService.NULL_SERVICE);
-    handler = new ExperimentalDomainHandler(server);
+    handler = new DiagnosticDomainHandler(server);
   });
 
-  group('ExperimentalDomainHandler', () {
+  group('DiagnosticDomainHandler', () {
     test('getDiagnostics', () async {
       String file = '/project/bin/test.dart';
       resourceProvider.newFile('/project/pubspec.yaml', 'name: project');
       resourceProvider.newFile(file, 'main() {}');
 
       server.setAnalysisRoots('0', ['/project/'], [], {});
 
       await server.onAnalysisComplete;
 
-      var request = new ExperimentalGetDiagnosticsParams().toRequest('0');
+      var request = new DiagnosticGetDiagnosticsParams().toRequest('0');
       var response = handler.handleRequest(request);
 
       int fileCount = MockSdk.LIBRARIES.length + 1 /* test.dart */;
 
       var json = response.toJson()[Response.RESULT];
       expect(json['contexts'], hasLength(1));
       var context = json['contexts'][0];
       expect(context['name'], '/project');
       expect(context['explicitFileCount'], fileCount);
       expect(context['implicitFileCount'], 0);
       expect(context['workItemQueueLength'], isNotNull);
     });
 
     test('getDiagnostics - (no root)', () async {
-      var request = new ExperimentalGetDiagnosticsParams().toRequest('0');
+      var request = new DiagnosticGetDiagnosticsParams().toRequest('0');
       var response = handler.handleRequest(request);
       var json = response.toJson()[Response.RESULT];
       expect(json['contexts'], hasLength(0));
     });
   });
 }