Add manual test for color space rendering behavior (#10000)

* Add manual test for color space rendering behavior

* Remove unneeded assets

* Add test for color demo

* Drag up to scroll down

dev/manual_tests/lib/color_testing_demo.dart

diff --git a/dev/manual_tests/lib/color_testing_demo.dart b/dev/manual_tests/lib/color_testing_demo.dart
new file mode 100644
index 0000000..6e3b7da
--- /dev/null
+++ b/dev/manual_tests/lib/color_testing_demo.dart
@@ -0,0 +1,95 @@
+// Copyright 2017 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/material.dart';
+import 'package:flutter/rendering.dart';
+
+class ColorTestingDemo extends StatelessWidget {
+  const ColorTestingDemo({ Key key }) : super(key: key);
+
+  static const String routeName = '/color_demo';
+
+  @override
+  Widget build(BuildContext context) => new ColorDemoHome();
+}
+
+const double _kPageMaxWidth = 500.0;
+
+class ColorDemoHome extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return new Scaffold(
+      appBar: new AppBar(title: const Text('Color Demo')),
+      body: new ListView(
+        padding: const EdgeInsets.all(5.0),
+        children: <Widget>[
+          new Image.network('https://flutter.github.io/assets-for-api-docs/tests/colors/gbr.png'),
+          new Image.network('https://flutter.github.io/assets-for-api-docs/tests/colors/tf.png'),
+          new Image.network('https://flutter.github.io/assets-for-api-docs/tests/colors/wide-gamut.png'),
+          const GradientRow(leftColor: const Color(0xFFFF0000), rightColor: const Color(0xFF00FF00)),
+          const GradientRow(leftColor: const Color(0xFF0000FF), rightColor: const Color(0xFFFFFF00)),
+          const GradientRow(leftColor: const Color(0xFFFF0000), rightColor: const Color(0xFF0000FF)),
+          const GradientRow(leftColor: const Color(0xFF00FF00), rightColor: const Color(0xFFFFFF00)),
+          const GradientRow(leftColor: const Color(0xFF0000FF), rightColor: const Color(0xFF00FF00)),
+          const GradientRow(leftColor: const Color(0xFFFF0000), rightColor: const Color(0xFFFFFF00)),
+
+          // For the following pairs, the blend result should match the opaque color.
+          const ColorRow(color: const Color(0xFFBCBCBC)),
+          const ColorRow(color: const Color(0x80000000)),
+
+          const ColorRow(color: const Color(0xFFFFBCBC)),
+          const ColorRow(color: const Color(0x80FF0000)),
+
+          const ColorRow(color: const Color(0xFFBCFFBC)),
+          const ColorRow(color: const Color(0x8000FF00)),
+
+          const ColorRow(color: const Color(0xFFBCBCFF)),
+          const ColorRow(color: const Color(0x800000FF)),
+        ],
+      ),
+    );
+  }
+}
+
+class GradientRow extends StatelessWidget {
+  const GradientRow({ Key key, this.rightColor, this.leftColor }) : super(key: key);
+
+  final Color leftColor;
+  final Color rightColor;
+
+  @override
+  Widget build(BuildContext context) {
+    return new Container(
+      height: 100.0,
+      decoration: new BoxDecoration(
+        gradient: new LinearGradient(
+          begin: FractionalOffset.topLeft,
+          end: FractionalOffset.bottomRight,
+          colors: <Color>[ leftColor, rightColor ],
+        ),
+      ),
+    );
+  }
+}
+
+class ColorRow extends StatelessWidget {
+  const ColorRow({ Key key, this.color }) : super(key: key);
+
+  final Color color;
+
+  @override
+  Widget build(BuildContext context) {
+    return new Container(
+      height: 100.0,
+      color: color,
+    );
+  }
+}
+
+void main() {
+  runApp(new MaterialApp(
+    title: 'Color Testing Demo',
+    home: new ColorDemoHome(),
+  ));
+}

dev/manual_tests/test/color_testing_demo_test.dart

diff --git a/dev/manual_tests/test/color_testing_demo_test.dart b/dev/manual_tests/test/color_testing_demo_test.dart
new file mode 100644
index 0000000..f7cb397
--- /dev/null
+++ b/dev/manual_tests/test/color_testing_demo_test.dart
@@ -0,0 +1,22 @@
+// Copyright 2017 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/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import '../lib/color_testing_demo.dart' as color_testing_demo;
+
+void main() {
+  testWidgets("Color testing demo smoke test", (WidgetTester tester) async {
+    color_testing_demo.main(); // builds the app and schedules a frame but doesn't trigger one
+    await tester.pump(); // see https://github.com/flutter/flutter/issues/1865
+    await tester.pump(); // triggers a frame
+
+    await tester.dragFrom(const Offset(0.0, 500.0), const Offset(0.0, 0.0)); // scrolls down
+    await tester.pump();
+
+    await tester.dragFrom(const Offset(0.0, 500.0), const Offset(0.0, 0.0)); // scrolls down
+    await tester.pump();
+  });
+}