Check the type of a hot reload report message (#7249)

See https://github.com/flutter/flutter/issues/7248

packages/flutter_tools/lib/src/hot.dart

@@ -394,7 +394,11 @@ class HotRunner extends ResidentRunner {
   }
 
   /// Returns [true] if the reload was successful.
-  bool _validateReloadReport(Map<String, dynamic> reloadReport) {
+  static bool validateReloadReport(Map<String, dynamic> reloadReport) {
+    if (reloadReport['type'] != 'ReloadReport') {
+      printError('Hot reload received invalid response: $reloadReport');
+      return false;
+    }
     if (!reloadReport['success']) {
       printError('Hot reload was rejected:');
       for (Map<String, dynamic> notice in reloadReport['details']['notices'])
@@ -479,7 +483,7 @@ class HotRunner extends ResidentRunner {
               pause: pause,
               rootLibPath: deviceEntryPath,
               packagesPath: devicePackagesPath);
-      if (!_validateReloadReport(reloadReport)) {
+      if (!validateReloadReport(reloadReport)) {
         // Reload failed.
         flutterUsage.sendEvent('hot', 'reload-reject');
         return new OperationResult(1, 'reload rejected');

packages/flutter_tools/test/all.dart

@@ -29,6 +29,7 @@ import 'devices_test.dart' as devices_test;
 import 'doctor_test.dart' as doctor_test;
 import 'drive_test.dart' as drive_test;
 import 'format_test.dart' as format_test;
+import 'hot_test.dart' as hot_test;
 import 'install_test.dart' as install_test;
 import 'logs_test.dart' as logs_test;
 import 'os_utils_test.dart' as os_utils_test;
@@ -65,6 +66,7 @@ void main() {
   doctor_test.main();
   drive_test.main();
   format_test.main();
+  hot_test.main();
   install_test.main();
   logs_test.main();
   os_utils_test.main();

packages/flutter_tools/test/hot_test.dart

+// Copyright 2016 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.
+
+import 'package:flutter_tools/src/hot.dart';
+import 'package:test/test.dart';
+
+import 'src/context.dart';
+
+void main()  {
+  group('validateReloadReport', () {
+    testUsingContext('invalid', () async {
+      expect(HotRunner.validateReloadReport(<String, dynamic>{}), false);
+      expect(HotRunner.validateReloadReport(
+          <String, dynamic>{'type': 'ReloadReport', 'success': true, 'details': <String, dynamic>{}}),
+          true);
+    });
+  });
+}