Make AssistContributor asynchronous.

pkg/analysis_server/test/abstract_context.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 testing.abstract_context;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/source/package_map_resolver.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/java_engine.dart' show CaughtException;
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 
 import 'mock_sdk.dart';
 
 /**
  * Finds an [Element] with the given [name].
  */
 Element findChildElement(Element root, String name, [ElementKind kind]) {
   Element result = null;
@@ skipping 61 matching lines @@
 
   void setUp() {
     setupResourceProvider();
     resourceResolver = new ResourceUriResolver(provider);
     packageMap = new Map<String, List<Folder>>();
     PackageMapUriResolver packageResolver =
         new PackageMapUriResolver(provider, packageMap);
     context = AnalysisEngine.instance.createAnalysisContext();
     context.sourceFactory =
         new SourceFactory([SDK_RESOLVER, packageResolver, resourceResolver]);
+    AnalysisEngine.instance.logger = PrintLogger.instance;
   }
 
   void setupResourceProvider() {
     provider = new MemoryResourceProvider();
   }
 
   void tearDown() {
     context = null;
     provider = null;
+    AnalysisEngine.instance.logger = null;
   }
 }
 
+/**
+ * Instances of the class [PrintLogger] print all of the errors.
+ */
+class PrintLogger implements Logger {
+  static final Logger instance = new PrintLogger();
+
+  @override
+  void logError(String message, [CaughtException exception]) {
+    print(message);
+    if (exception != null) {
+      print(exception);
+    }
+  }
+
+  @override
+  void logError2(String message, Object exception) {
+    print(message);
+    if (exception != null) {
+      print(exception);
+    }
+  }
+
+  @override
+  void logInformation(String message, [CaughtException exception]) {
+    print(message);
+    if (exception != null) {
+      print(exception);
+    }
+  }
+
+  @override
+  void logInformation2(String message, Object exception) {
+    print(message);
+    if (exception != null) {
+      print(exception);
+    }
+  }
+}
+
 /**
  * Wraps the given [_ElementVisitorFunction] into an instance of
  * [engine.GeneralizingElementVisitor].
  */
 class _ElementVisitorFunctionWrapper extends GeneralizingElementVisitor {
   final _ElementVisitorFunction function;
   _ElementVisitorFunctionWrapper(this.function);
   visitElement(Element element) {
     function(element);
     super.visitElement(element);
   }
 }