Testing in Flutter

Sep 19 2023 · Dart 2.19.3, Flutter 3.7.6, Android Studio 2021.3.1, Visual Studio Code 1.7.4

Part 5: Generate Goldens

16. Widget Extension Functions

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Previous episode: 15. Generate Your First Golden Next episode: 17. Widget Test for Multiple Screen Sizes

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An extension function is a member function of a class that is defined outside the class. Extension functions are declared with the receiver type as a prefix to the function’s name. In this case, we are creating an extension function for the WidgetTester class.

extension WidgetTesterExtension on WidgetTester{

Future setScreenSize() async {
   binding.window.physicalSizeTestValue = Size(1080, 1920);
   binding.window.devicePixelRatioTestValue = 2.625;
   binding.platformDispatcher.textScaleFactorTestValue = 1.0;

// Google Pixel 2
const double PIXEL_2_HEIGHT = 1920;
const double PIXEL_2_WIDTH = 1080;

// iphone 13
const double IPHONE_13_HEIGHT = 2532;
const double IPHONE_13_WIDTH = 1170;

// iphone 13 device pixel ratio
const double IPHONE_13_PIXEL_RATIO = 3.0;

// galaxy tab
const double GALAXY_TAB_HEIGHT = 2560;
const double GALAXY_TAB_WIDTH = 1600;

// ipad pro pixel ratio
const double IPAD_PRO_PIXEL_RATIO = 4.0;

// pixel 2 pixel ratio
const double PIXEL_2_PIXEL_RATIO = 2.625;

// ipad pro
const double IPAD_PRO_HEIGHT = 2732;
const double IPAD_PRO_WIDTH = 2048;
class TestCaseScreenInfo {
  final String deviceName;
  final Size screenSize;
  final double pixedRatio;
  final double textScaleValue;

  const TestCaseScreenInfo(
      {required this.deviceName,
      required this.screenSize,
      required this.pixedRatio,
      required this.textScaleValue});

const testCaseScreenInfoList = [
  // Pixel 2 Portrait
      deviceName: 'Pixel-2-Portrait',
      screenSize: Size(PIXEL_2_WIDTH, PIXEL_2_HEIGHT),
      pixedRatio: PIXEL_2_PIXEL_RATIO,
      textScaleValue: 1.0),

  // Pixel 2 Landscape
      deviceName: 'Pixel-2-Landscape',
      screenSize: Size(PIXEL_2_HEIGHT, PIXEL_2_WIDTH),
      pixedRatio: PIXEL_2_PIXEL_RATIO,
      textScaleValue: 1.0),

  // iphone 13 Portrait
      deviceName: 'iphone-13-Portrait',
      screenSize: Size(IPHONE_13_WIDTH, IPHONE_13_HEIGHT),
      pixedRatio: IPHONE_13_PIXEL_RATIO,
      textScaleValue: 1.0),

  // iphone 13 Landscape
      deviceName: 'iphone-13-Landscape',
      screenSize: Size(IPHONE_13_HEIGHT, IPHONE_13_WIDTH),
      pixedRatio: IPHONE_13_PIXEL_RATIO,
      textScaleValue: 1.0),

  // ipad pro Portrait
      deviceName: 'ipad-pro-Portrait',
      screenSize: Size(IPAD_PRO_WIDTH, IPAD_PRO_HEIGHT),
      pixedRatio: IPAD_PRO_PIXEL_RATIO,
      textScaleValue: 1.0),

  // ipad pro Landscape
      deviceName: 'ipad-pro-Landscape',
      screenSize: Size(IPAD_PRO_HEIGHT, IPAD_PRO_WIDTH),
      pixedRatio: IPAD_PRO_PIXEL_RATIO,
      textScaleValue: 1.0),

  // galaxy tab Portrait
      deviceName: 'galaxy-tab-Portrait',
      pixedRatio: IPAD_PRO_PIXEL_RATIO,
      textScaleValue: 1.0),

  // galaxy tab Landscape
      deviceName: 'galaxy-tab-Landscape',
      pixedRatio: IPAD_PRO_PIXEL_RATIO,
      textScaleValue: 1.0),
Future setScreenSize(TestCaseScreenInfo testCaseScreenInfo) async {

  binding.platformDispatcher.textScaleFactorTestValue =
  binding.window.physicalSizeTestValue = testCaseScreenInfo.screenSize;
  binding.window.devicePixelRatioTestValue = testCaseScreenInfo.pixedRatio;

Future testMultipleScreenSize(String testName, 
Future<void> Function(WidgetTester, TestCaseScreenInfo testCase),
  testFunction) async =>testCaseScreenInfoList.forEach((testCase) {
Future testWidgetsMultipleScreenSizes(
      String testName,
      Future<void> Function(WidgetTester, TestCaseScreenInfo testCase)
          testFunction) async =>
  testCaseScreenInfoList.forEach((testCase) async {
    testWidgets("$testName-${testCase.deviceName}", (tester) async {
      await tester.setScreenSize(testCase);
      await testFunction(tester, testCase);