Add Observatory mojo_shell hearbeat test

mojo/dart/observatory_tester/tester.dart

Index: mojo/dart/observatory_tester/tester.dart
diff --git a/mojo/dart/observatory_tester/tester.dart b/mojo/dart/observatory_tester/tester.dart
new file mode 100644
index 0000000000000000000000000000000000000000..28a3ddd57b8fd2cb9578eb9b0fded400bbfd3ade
--- /dev/null
+++ b/mojo/dart/observatory_tester/tester.dart
@@ -0,0 +1,187 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+library observatory_tester;
+
+// Minimal dependency Observatory heartbeat test.
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+class Expect {
+  static equals(a, b) {
+    if (a != b) {
+      throw 'Expected $a == $b';
+    }
+  }
+
+  static isMap(a) {
+    if (a is! Map) {
+      throw 'Expected $a to be a Map';
+    }
+  }
+
+  static notExecuted() {
+    throw 'Should not have hit';
+  }
+
+  static isNotNull(a) {
+    if (a == null) {
+      throw 'Expected $a to not be null.';
+    }
+  }
+}
+
+class Launch {
+  Launch(this.executable, this.arguments, this.process, this.port) {
+    _killRequested = false;
+    this.process.exitCode.then(_checkKill);
+  }
+
+  void kill() {
+    _killRequested = true;
+    process.kill();
+  }
+
+  void _checkKill(int exitCode) {
+    if (!_killRequested) {
+      throw 'Unexpected exit of testee. (exitCode = $exitCode)';
+    }
+  }
+
+  final String executable;
+  final String arguments;
+  final Process process;
+  final int port;
+  bool _killRequested;
+}
+
+class Launcher {
+  /// Launch [executable] with [arguments]. Returns a future to a [Launch]
+  /// which includes the process and port where Observatory is running.
+  static Future<Launch> launch(String executable,
+                               List<String> arguments) async {
+    var process = await Process.start(executable, arguments);
+
+    // Completer completes once 'Observatory listening on' message has been
+    // scraped and we know the port number.
+    var completer = new Completer();
+
+    process.stdout.transform(UTF8.decoder)
+                  .transform(new LineSplitter()).listen((line) {
+      if (line.startsWith('Observatory listening on http://')) {
+        RegExp portExp = new RegExp(r"\d+.\d+.\d+.\d+:(\d+)");
+        var port = portExp.firstMatch(line).group(1);
+        var portNumber = int.parse(port);
+        completer.complete(portNumber);
+      } else {
+        print(line);
+      }
+    });
+
+    process.stderr.transform(UTF8.decoder)
+                  .transform(new LineSplitter()).listen((line) {
+      print(line);
+    });
+
+    var port = await completer.future;
+    return new Launch(executable, arguments, process, port);
+  }
+}
+
+class ServiceHelper {
+  ServiceHelper(this.client) {
+    client.listen(_onData,
+                  onError: _onError,
+                  cancelOnError: true);
+  }
+
+  Future<Map> invokeRPC(String method, [Map params]) async {
+    var key = _createKey();
+    var request = JSON.encode({
+      'jsonrpc': '2.0',
+      'method': method,
+      'params': params == null ? {} : params,
+      'id': key,
+    });
+    client.add(request);
+    var completer = new Completer();
+    _outstanding_requests[key] = completer;
+    print('-> $key ($method)');
+    return completer.future;
+  }
+
+  String _createKey() {
+    var key = '$_id';
+    _id++;
+    return key;
+  }
+
+  void _onData(String message) {
+    var response = JSON.decode(message);
+    var key = response['id'];
+    print('<- $key');
+    var completer = _outstanding_requests.remove(key);
+    assert(completer != null);
+    var result = response['result'];
+    var error = response['error'];
+    if (error != null) {
+      assert(result == null);
+      completer.completeError(error);
+    } else {
+      assert(result != null);
+      completer.complete(result);
+    }
+  }
+
+  void _onError(error) {
+    print('WebSocket error: $error');
+  }
+
+  final WebSocket client;
+  final Map<String, Completer> _outstanding_requests = <String, Completer>{};
+  var _id = 1;
+}
+
+main(List<String> args) async {
+  var executable = args[0];
+  var arguments = args.sublist(1);
+
+  print('Launching $executable with $arguments');
+
+  var launch = await Launcher.launch(executable, arguments);
+
+  print('Observatory is on port ${launch.port}');
+  var serviceUrl = 'ws://127.0.0.1:${launch.port}/ws';
+
+  var client = await WebSocket.connect(serviceUrl);
+  print('Connected to $serviceUrl');
+
+  var helper = new ServiceHelper(client);
+
+  // Invoke getVM RPC. Verify a valid repsonse.
+  var vm = await helper.invokeRPC('getVM');
+  Expect.equals(vm['type'], 'VM');
+
+  // Invoke a bogus RPC. Expect an error.
+  bool errorCaught = false;
+  try {
+    var bad = await helper.invokeRPC('BARTSIMPSON');
+    Expect.notExecuted();
+  } catch (e) {
+    errorCaught = true;
+    // Map.
+    Expect.isMap(e);
+    // Has an error code.
+    Expect.isNotNull(e['code']);
+  }
+  Expect.equals(errorCaught, true);
+
+  await client.close();
+  print('Closed connection');
+
+  print('Finished.');
+  launch.kill();
+}