Integration test search.getTypeHierarchy and make some minor fixes.

pkg/analysis_server/lib/src/search/search_domain.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 search.domain;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/computer/element.dart' as se;
@@ skipping 119 matching lines @@
 
   /**
    * Implement the `search.getTypeHierarchy` request.
    */
   Response getTypeHierarchy(Request request) {
     // prepare parameters
     String file = request.getRequiredParameter(FILE).asString();
     int offset = request.getRequiredParameter(OFFSET).asInt();
     // prepare Element
     List<Element> elements = server.getElementsAtOffset(file, offset);
+    Response response = new Response(request.id);
     if (elements.isEmpty) {
-      return new Response(request.id);
+      response.setEmptyResult();

[scheglov, 2014/08/08 18:40:33]

I don't understand why we do this.
The field should be absent, and it is null by default, right?

[Paul Berry, 2014/08/08 19:23:04]

Without this call the response message would be

  {"id": ...}

But it the spec defines the response format as:

  response: {
    "id": String
    "error": optional Error
    "result": {
      "hierarchyItems": optional List<TypeHierarchyItem>
    }
  }

which implies that the response should be:

  {"id": ..., "result": {}}

The call to setEmptyResult() ensures that "result": {} is present.

+      return response;
     }
     Element element = elements.first;
     // prepare type hierarchy
     TypeHierarchyComputer computer = new TypeHierarchyComputer(searchEngine);
     computer.compute(element).then((List<TypeHierarchyItem> items) {
-      Response response = new Response(request.id);
-      response.setResult(HIERARCHY_ITEMS, objectToJson(items));
+      if (items != null) {
+        response.setResult(HIERARCHY_ITEMS, objectToJson(items));
+      } else {
+        response.setEmptyResult();

[scheglov, 2014/08/08 18:40:33]

Same here.

+      }
       server.sendResponse(response);
     });
     // delay response
     return Response.DELAYED_RESPONSE;
   }
 
   @override
   Response handleRequest(Request request) {
     try {
       String requestName = request.method;
@@ skipping 20 matching lines @@
     notification.setParameter(ID, searchId);
     notification.setParameter(LAST, isLast);
     notification.setParameter(RESULTS, results);
     server.sendNotification(notification);
   }
 
   static SearchResult toResult(SearchMatch match) {
     return new SearchResult.fromMatch(match);
   }
 }