Merge pull request comigor#2 from Igor1201/poc/multiple-screenshots

[POC] Multiple screenshots

.gitignore

@@ -69,3 +69,6 @@ build/
 !**/ios/**/default.pbxuser
 !**/ios/**/default.perspectivev3
 !/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages
+
+showcase/
+

lib/components/my_widget.dart

@@ -1,8 +1,27 @@
 import 'package:flutter/material.dart';
 
 class MyWidget extends StatelessWidget {
+  final bool anotherBuild;
+  final double sliderValue;
+
+  MyWidget({
+    this.anotherBuild = false,
+    this.sliderValue = 2.0,
+  });
+
   @override
   Widget build(BuildContext context) {
+    if (anotherBuild) {
+      return Row(
+        mainAxisAlignment: MainAxisAlignment.center,
+        children: [
+          Container(color: Colors.red, width: 40.0, height: 40.0),
+          Container(color: Colors.green, width: 40.0, height: 40.0),
+          Container(color: Colors.blue, width: 40.0, height: 40.0),
+        ],
+      );
+    }
+
     return Column(
       mainAxisAlignment: MainAxisAlignment.center,
       children: [
@@ -18,7 +37,7 @@ class MyWidget extends StatelessWidget {
           value: true,
         ),
         Slider(
-          value: 2.0,
+          value: sliderValue,
           max: 7.0,
           onChanged: (_) {},
         ),

test/components/my_widget_test.dart

@@ -1,17 +1,29 @@
 import 'package:flutter_test/flutter_test.dart';
-
+import 'package:flutter/material.dart';
 import 'package:showcase/components/my_widget.dart';
-import '../helpers/golden_boundary.dart';
+import '../helpers/showcase.dart';
 
 void main() {
-  testWidgets('MyWidget golden', (WidgetTester tester) async {
-    await tester.pumpWidget(GoldenBoundary(
-      child: MyWidget(),
-    ));
+  group('Showcase widgets', () {
+    final widgetList = [
+      MyWidget(),
+      MyWidget(anotherBuild: true),
+      MyWidget(sliderValue: 5.0),
+    ];
 
-    await expectLater(
-      find.byType(MyWidget),
-      matchesGoldenFile('golden.png'),
+    showcaseWidgets(widgetList, customContainerBuilder: (child) => Container(
+        padding: EdgeInsets.all(12.0),
+        decoration: BoxDecoration(
+          color: Colors.amberAccent,
+          border: Border.all(
+            color: Colors.amber,
+            width: 2.0,
+          ),
+        ),
+        width: 800.0,
+        height: 240.0,
+        child: child,
+      ),
     );
   });
 }

test/components/my_widget_test_golden.dart

@@ -0,0 +1,17 @@
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:showcase/components/my_widget.dart';
+import '../helpers/golden_boundary.dart';
+
+void main() {
+  testWidgets('MyWidget golden', (WidgetTester tester) async {
+    await tester.pumpWidget(GoldenBoundary(
+      child: MyWidget(),
+    ));
+
+    await expectLater(
+      find.byType(MyWidget),
+      matchesGoldenFile('golden.png'),
+    );
+  });
+}

test/helpers/golden_boundary.dart

@@ -1,21 +1,37 @@
 import 'package:flutter/material.dart';
 
+typedef ContainerBuilder = Container Function(Widget child);
+
 class GoldenBoundary extends StatelessWidget {
   final Widget child;
+  final GlobalKey globalKey;
+  final ContainerBuilder customContainerBuilder;
+
+
+  GoldenBoundary({
+    @required this.child,
+    this.globalKey,
+    this.customContainerBuilder,
+  });
 
-  GoldenBoundary({@required this.child});
+  Widget _defaultContainerBuilder(Widget child) {
+    return Container(
+      padding: EdgeInsets.all(10.0),
+      width: 640.0,
+      height: 480.0,
+      child: child,
+    );
+  }
 
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
       home: Scaffold(
         body: RepaintBoundary(
-          child: Container(
-            padding: EdgeInsets.all(10.0),
-            width: 640.0,
-            height: 480.0,
-            child: child,
-          ),
+          key: globalKey,
+          child: customContainerBuilder != null ?
+              customContainerBuilder(child) :
+              _defaultContainerBuilder(child),
         ),
       ),
     );

test/helpers/showcase.dart

@@ -0,0 +1 @@
+export './showcase_widgets.dart' show showcaseWidgets;

test/helpers/showcase_widgets.dart

@@ -0,0 +1,49 @@
+import 'dart:async';
+import 'dart:typed_data';
+import 'dart:io';
+import 'dart:ui' as ui;
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+
+import './golden_boundary.dart';
+
+Future<Uint8List> capturePng(WidgetTester tester, GlobalKey key) async {
+  RenderRepaintBoundary boundary = key.currentContext.findRenderObject();
+  ui.Image image = await boundary.toImage();
+  ByteData byteData =
+      await image.toByteData(format: ui.ImageByteFormat.png);
+  return byteData.buffer.asUint8List();
+}
+
+Future<File> writeToFile(String path, Uint8List imageBytes) async {
+  final File output = File(path);
+  output.createSync(recursive: true);
+  return await output.writeAsBytes(imageBytes);
+}
+
+void makeTest(Widget widget, int index, {ContainerBuilder customContainerBuilder, String outDir}) async {
+  final strIndex = index.toString().padLeft(3, '0');
+  testWidgets('[$strIndex] Showcasing ${widget.toString()}', (WidgetTester tester) async {
+    // https://github.com/flutter/flutter/issues/17738#issuecomment-392237064
+    await tester.runAsync(() async {
+      final key = GlobalKey();
+
+      await tester.pumpWidget(GoldenBoundary(
+        globalKey: key,
+        child: widget,
+        customContainerBuilder: customContainerBuilder,
+      ));
+
+      final screenshotBytes = await capturePng(tester, key);
+      await writeToFile('${outDir ?? 'showcase'}/${strIndex}_${widget.toString()}.png', screenshotBytes);
+    });
+  });
+}
+
+showcaseWidgets(List<Widget> widgets, {ContainerBuilder customContainerBuilder, String outDir}) {
+  widgets
+      .asMap()
+      .forEach((index, widget) => makeTest(widget, index, customContainerBuilder: customContainerBuilder, outDir: outDir));
+}