Add a diagnostic.getServerPort analysis server request.

pkg/analysis_server/test/integration/diagnostic/get_server_port_test.dart

+// Copyright (c) 2017, 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.
+
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:analysis_server/plugin/protocol/protocol.dart';
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../integration_tests.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(GetServerPortTest);
+  });
+}
+
+@reflectiveTest
+class GetServerPortTest extends AbstractAnalysisServerIntegrationTest {
+  test_connect() async {
+    standardAnalysisSetup();
+
+    DiagnosticGetServerPortResult result = await sendDiagnosticGetServerPort();
+    expect(result.port, isNotNull);
+    expect(result.port, isNonZero);
+
+    // Connect to the server and verify that it's serving the status page.
+    HttpClient client = new HttpClient();
+    HttpClientRequest request = await client
+        .getUrl(Uri.parse('http://localhost:${result.port}/status'));
+    HttpClientResponse response = await request.close();
+    String responseBody = await UTF8.decodeStream(response);
+    expect(responseBody, contains('<title>Analysis Server</title>'));
+  }
+
+  @override
+  bool get enableNewAnalysisDriver => true;
+}