From c4afe9589bb0a9aa804ee8482332536cc5e8cb96 Mon Sep 17 00:00:00 2001
From: Chris Bracken <chris@bracken.jp>
Date: Mon, 28 Nov 2016 11:11:03 -0800
Subject: [PATCH] Add getRenderTree() to Flutter Driver (#7007)

Returns a dump of the application's render tree.
---
 packages/flutter_driver/lib/src/driver.dart   |  6 +++
 .../flutter_driver/lib/src/extension.dart     |  8 ++++
 .../flutter_driver/lib/src/render_tree.dart   | 37 +++++++++++++++++++
 3 files changed, 51 insertions(+)
 create mode 100644 packages/flutter_driver/lib/src/render_tree.dart

diff --git a/packages/flutter_driver/lib/src/driver.dart b/packages/flutter_driver/lib/src/driver.dart
index 71600ee6c93..0ebc45c8381 100644
--- a/packages/flutter_driver/lib/src/driver.dart
+++ b/packages/flutter_driver/lib/src/driver.dart
@@ -16,6 +16,7 @@ import 'gesture.dart';
 import 'health.dart';
 import 'input.dart';
 import 'message.dart';
+import 'render_tree.dart';
 import 'timeline.dart';
 
 /// Timeline stream identifier.
@@ -244,6 +245,11 @@ class FlutterDriver {
     return Health.fromJson(await _sendCommand(new GetHealth()));
   }
 
+  /// Returns a dump of the render tree.
+  Future<RenderTree> getRenderTree() async {
+    return RenderTree.fromJson(await _sendCommand(new GetRenderTree()));
+  }
+
   /// Taps at the center of the widget located by [finder].
   Future<Null> tap(SerializableFinder finder) async {
     await _sendCommand(new Tap(finder));
diff --git a/packages/flutter_driver/lib/src/extension.dart b/packages/flutter_driver/lib/src/extension.dart
index 6ffcdaf3a22..f4861f1f44c 100644
--- a/packages/flutter_driver/lib/src/extension.dart
+++ b/packages/flutter_driver/lib/src/extension.dart
@@ -6,6 +6,7 @@ import 'dart:async';
 
 import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart' show RendererBinding;
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -16,6 +17,7 @@ import 'gesture.dart';
 import 'health.dart';
 import 'input.dart';
 import 'message.dart';
+import 'render_tree.dart';
 
 const String _extensionMethodName = 'driver';
 const String _extensionMethod = 'ext.flutter.$_extensionMethodName';
@@ -61,6 +63,7 @@ class _FlutterDriverExtension {
   _FlutterDriverExtension._() {
     _commandHandlers.addAll(<String, CommandHandlerCallback>{
       'get_health': _getHealth,
+      'get_render_tree': _getRenderTree,
       'tap': _tap,
       'get_text': _getText,
       'scroll': _scroll,
@@ -72,6 +75,7 @@ class _FlutterDriverExtension {
 
     _commandDeserializers.addAll(<String, CommandDeserializerCallback>{
       'get_health': GetHealth.deserialize,
+      'get_render_tree': GetRenderTree.deserialize,
       'tap': Tap.deserialize,
       'get_text': GetText.deserialize,
       'scroll': Scroll.deserialize,
@@ -135,6 +139,10 @@ class _FlutterDriverExtension {
 
   Future<Health> _getHealth(Command command) async => new Health(HealthStatus.ok);
 
+  Future<RenderTree> _getRenderTree(Command command) async {
+    return new RenderTree(RendererBinding.instance?.renderView?.toStringDeep());
+  }
+
   /// Runs `finder` repeatedly until it finds one or more [Element]s, or times out.
   ///
   /// The timeout is five seconds.
diff --git a/packages/flutter_driver/lib/src/render_tree.dart b/packages/flutter_driver/lib/src/render_tree.dart
new file mode 100644
index 00000000000..b3b5ad0f1e4
--- /dev/null
+++ b/packages/flutter_driver/lib/src/render_tree.dart
@@ -0,0 +1,37 @@
+// 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 'message.dart';
+
+/// A request for a string representation of the render tree.
+class GetRenderTree implements Command {
+  @override
+  final String kind = 'get_render_tree';
+
+  /// Deserializes the command from JSON generated by [serialize].
+  static GetRenderTree deserialize(Map<String, String> json) => new GetRenderTree();
+
+  @override
+  Map<String, String> serialize() => const <String, String>{};
+}
+
+/// A string representation of the render tree.
+class RenderTree extends Result {
+  /// Creates a [RenderTree] object with the given string representation.
+  RenderTree(this.tree);
+
+  /// Deserializes the result from JSON.
+  static RenderTree fromJson(Map<String, dynamic> json) {
+    return new RenderTree(json['tree']);
+  }
+
+  /// String representation of the render tree.
+  final String tree;
+
+  @override
+  Map<String, dynamic> toJson() => <String, dynamic>{
+    'tree': tree
+  };
+}
+