Wait for analysis in search domain. Rewrite with async/await.

pkg/analysis_server/test/search/top_level_declarations_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.search.top_level_declarations;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 17 matching lines @@
     }
   }
 
   void assertNoDeclaration(ElementKind kind, String name) {
     result = findTopLevelResult(kind, name);
     if (result != null) {
       fail('Unexpected: kind=$kind name="$name"\nin\n' + results.join('\n'));
     }
   }
 
-  Future findTopLevelDeclarations(String pattern) {
-    return waitForTasksFinished().then((_) {
-      Request request =
-          new SearchFindTopLevelDeclarationsParams(pattern).toRequest('0');
-      Response response = handleSuccessfulRequest(request);
-      searchId =
-          new SearchFindTopLevelDeclarationsResult.fromResponse(response).id;
-      results.clear();
-      return waitForSearchResults();
-    });
+  Future findTopLevelDeclarations(String pattern) async {
+    await waitForTasksFinished();
+    Request request =
+        new SearchFindTopLevelDeclarationsParams(pattern).toRequest('0');
+    Response response = await waitResponse(request);
+    searchId =
+        new SearchFindTopLevelDeclarationsResult.fromResponse(response).id;
+    return waitForSearchResults();
   }
 
   SearchResult findTopLevelResult(ElementKind kind, String name) {
     for (SearchResult result in results) {
       Element element = result.path[0];
       if (element.kind == kind && element.name == name) {
         return result;
       }
     }
     return null;
   }
 
-  test_startEndPattern() {
+  test_startEndPattern() async {
     addTestFile('''
 class A {} // A
 class B = Object with A;
 typedef C();
 D() {}
 var E = null;
 class ABC {}
 ''');
-    return findTopLevelDeclarations('^[A-E]\$').then((_) {
-      assertHasDeclaration(ElementKind.CLASS, 'A');
-      assertHasDeclaration(ElementKind.CLASS, 'B');
-      assertHasDeclaration(ElementKind.FUNCTION_TYPE_ALIAS, 'C');
-      assertHasDeclaration(ElementKind.FUNCTION, 'D');
-      assertHasDeclaration(ElementKind.TOP_LEVEL_VARIABLE, 'E');
-      assertNoDeclaration(ElementKind.CLASS, 'ABC');
-    });
+    await findTopLevelDeclarations('^[A-E]\$');
+    assertHasDeclaration(ElementKind.CLASS, 'A');
+    assertHasDeclaration(ElementKind.CLASS, 'B');
+    assertHasDeclaration(ElementKind.FUNCTION_TYPE_ALIAS, 'C');
+    assertHasDeclaration(ElementKind.FUNCTION, 'D');
+    assertHasDeclaration(ElementKind.TOP_LEVEL_VARIABLE, 'E');
+    assertNoDeclaration(ElementKind.CLASS, 'ABC');
   }
 }