integrationDriver function Null safety

Future<void> integrationDriver(
  1. {FlutterDriver? driver,
  2. ScreenshotCallback? onScreenshot}

Adaptor to run an integration test using flutter drive.

To an integration test <test_name>.dart using flutter drive, put a file named <test_name>_test.dart in the app's test_driver directory:

import 'dart:async';

import 'package:integration_test/integration_test_driver_extended.dart';

Future<void> main() async {
  final FlutterDriver driver = await FlutterDriver.connect();
  await integrationDriver(
    driver: driver,
    onScreenshot: (String screenshotName, List<int> screenshotBytes) async {
      return true;


driver A custom driver. Defaults to FlutterDriver.connect().

onScreenshot can be used to process the screenshots taken during the test. An example could be that this callback compares the byte array against a baseline image, and it returns true if both images are equal.

As a result, returning false from onScreenshot will make the test fail.


Future<void> integrationDriver(
    {FlutterDriver? driver, ScreenshotCallback? onScreenshot}) async {
  driver ??= await FlutterDriver.connect();
  // Test states that it's waiting on web driver commands.
  // [DriverTestMessage] is converted to string since json format causes an
  // error if it's used as a message for requestData.
  String jsonResponse = await driver.requestData(DriverTestMessage.pending().toString());

  Response response = Response.fromJson(jsonResponse);

  // Until `integration_test` returns a [WebDriverCommandType.noop], keep
  // executing WebDriver commands.
  while ( != null &&!['web_driver_command'] != null &&!['web_driver_command'] != '${WebDriverCommandType.noop}') {
    final String? webDriverCommand =!['web_driver_command'] as String?;
    if (webDriverCommand == '${WebDriverCommandType.screenshot}') {
      assert(onScreenshot != null, 'screenshot command requires an onScreenshot callback');
      // Use `driver.screenshot()` method to get a screenshot of the web page.
      final List<int> screenshotImage = await driver.screenshot();
      final String screenshotName =!['screenshot_name']! as String;

      final bool screenshotSuccess = await onScreenshot!(screenshotName, screenshotImage);
      if (screenshotSuccess) {
        jsonResponse = await driver.requestData(DriverTestMessage.complete().toString());
      } else {
        jsonResponse =
            await driver.requestData(DriverTestMessage.error().toString());

      response = Response.fromJson(jsonResponse);
    } else if (webDriverCommand == '${WebDriverCommandType.ack}') {
      // Previous command completed ask for a new one.
      jsonResponse =
          await driver.requestData(DriverTestMessage.pending().toString());

      response = Response.fromJson(jsonResponse);
    } else {

  // If No-op command is sent, ask for the result of all tests.
  if ( != null &&!['web_driver_command'] != null &&!['web_driver_command'] == '${WebDriverCommandType.noop}') {
    jsonResponse = await driver.requestData(null);

    response = Response.fromJson(jsonResponse);
    print('result $jsonResponse');

  if ( != null &&!['screenshots'] != null && onScreenshot != null) {
    final List<dynamic> screenshots =!['screenshots'] as List<dynamic>;
    final List<String> failures = <String>[];
    for (final dynamic screenshot in screenshots) {
      final Map<String, dynamic> data = screenshot as Map<String, dynamic>;
      final List<dynamic> screenshotBytes = data['bytes'] as List<dynamic>;
      final String screenshotName = data['screenshotName'] as String;

      bool ok = false;
      try {
        ok = await onScreenshot(screenshotName, screenshotBytes.cast<int>());
      } catch (exception) {
        throw StateError(
          'Screenshot failure:\n'
          'onScreenshot("$screenshotName", <bytes>) threw an exception: $exception',
      if (!ok) {
    if (failures.isNotEmpty) {
     throw StateError('The following screenshot tests failed: ${failures.join(', ')}');

  await driver.close();

  if (response.allTestsPassed) {
    print('All tests passed.');
  } else {
    print('Failure Details:\n${response.formattedFailureDetails}');