add sdkPath and enable tests

pkg/analysis_server/test/mocks.dart

Index: pkg/analysis_server/test/mocks.dart
diff --git a/pkg/analysis_server/test/mocks.dart b/pkg/analysis_server/test/mocks.dart
index 88a6744c908c20e1ab6b1d67540ac375126fee66..82b15fa88d5b7db145336f54fdc30106719ea831 100644
--- a/pkg/analysis_server/test/mocks.dart
+++ b/pkg/analysis_server/test/mocks.dart
@@ -7,14 +7,29 @@ library mocks;
 import 'dart:async';
 import 'dart:io';
 
+import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/channel.dart';
 import 'package:analysis_server/src/protocol.dart';
+import 'package:unittest/matcher.dart';
+
+/**
+ * Answer the path the the SDK relative to the currently running script
+ * or throw an exception if it cannot be found.
+ */
+String get sdkPath {
+  Uri sdkUri = Uri.base.resolveUri(Platform.script).resolve('../../../sdk/');
+  // Verify that the internal library file exists
+  Uri libFileUri = sdkUri.resolve('lib/_internal/libraries.dart');
+  if (!new File.fromUri(libFileUri).existsSync()) {
+    throw 'Expected Dart SDK at ${sdkUri.path}';
+  }
+  return sdkUri.path;
+}
 
 /**
  * A mock [WebSocket] for testing.
  */
 class MockSocket<T> implements WebSocket {
-
   StreamController controller = new StreamController();
   MockSocket twin;
   Stream stream;
@@ -51,18 +66,48 @@ class MockSocket<T> implements WebSocket {
 }
 
 /**
- * A mock [ServerCommunicationChannel] channel that does nothing.
+ * A mock [ServerCommunicationChannel] for testing [AnalysisServer].
  */
 class MockServerChannel implements ServerCommunicationChannel {
+  StreamController<Request> requestController = new StreamController<Request>();
+  StreamController<Response> responseController = new StreamController<Response>();
+  StreamController<Notification> notificationController = new StreamController<Notification>();
+
+  List<Response> responsesReceived = [];
+  List<Notification> notificationsReceived = [];
+
+  MockServerChannel() {
+  }
+
   @override
   void listen(void onRequest(Request request), {void onError(), void onDone()}) {
+    requestController.stream.listen(onRequest, onError: onError, onDone: onDone);
   }
 
   @override
   void sendNotification(Notification notification) {
+    notificationsReceived.add(notification);
+    // Wrap send notification in future to simulate websocket
+    new Future(() => notificationController.add(notification));
+  }
+
+  /// Simulate request/response pair
+  Future<Response> sendRequest(Request request) {
+    var id = request.id;
+    // Wrap send request in future to simulate websocket
+    new Future(() => requestController.add(request));
+    return responseController.stream.firstWhere((response) => response.id == id);
   }
 
   @override
   void sendResponse(Response response) {
+    responsesReceived.add(response);
+    // Wrap send response in future to simulate websocket
+    new Future(() => responseController.add(response));
+  }
+
+  void expectMsgCount({responseCount: 0, notificationCount: 0}) {
+    expect(responsesReceived, hasLength(responseCount));
+    expect(notificationsReceived, hasLength(notificationCount));
   }
 }