Flutter行为驱动开发插件flutter_gherkin的使用

简介

flutter_gherkin 是一个功能齐全的Gherkin解析器和测试运行器，适用于Flutter和Dart 2。它遵循Cucumber的各种形式，提供了一种行为驱动开发（BDD）的方法来编写和执行测试。

安装与配置

添加依赖

在 pubspec.yaml 文件中添加 flutter_gherkin 依赖：

dev_dependencies:
  flutter_gherkin: ^x.x.x # 替换为最新版本号

创建可测试应用

创建一个名为 test_driver/app.dart 的文件，并启用Flutter Driver扩展：

import 'package:flutter_driver/driver_extension.dart';
import 'package:your_app/main.dart' as app;

void main() {
  enableFlutterDriverExtension();
  app.main();
}

编写Feature文件

在 test_driver/features 目录下创建 .feature 文件，例如 counter.feature：

Feature: Counter
  The counter should be incremented when the button is pressed.

  Scenario: Counter increases when the button is pressed
    Given I expect the "counter" to be "0"
    When I tap the "increment" button 10 times
    Then I expect the "counter" to be "10"

实现步骤定义

创建一个自定义步骤定义类，例如 tap_button_n_times_step.dart：

import 'package:flutter_driver/flutter_driver.dart';
import 'package:flutter_gherkin/flutter_gherkin.dart';
import 'package:gherkin/gherkin.dart';

StepDefinitionGeneric TapButtonNTimesStep() {
  return when2<String, int, FlutterWorld>(
    'I tap the {string} button {int} times',
    (key, count, context) async {
      final locator = find.byValueKey(key);
      for (var i = 0; i < count; i++) {
        await FlutterDriverUtils.tap(context.world.driver, locator);
      }
    },
  );
}

配置测试

创建 test_driver/app_test.dart 文件并配置测试：

import 'dart:async';
import 'package:flutter_gherkin/flutter_gherkin.dart';
import 'package:gherkin/gherkin.dart';
import 'steps/tap_button_n_times_step.dart';

Future<void> main() {
  final config = FlutterTestConfiguration()
    ..features = [RegExp(r'test_driver/features/*.feature')]
    ..reporters = [
      ProgressReporter(),
      TestRunSummaryReporter(),
      JsonReporter(path: './report.json')
    ]
    ..stepDefinitions = [TapButtonNTimesStep()]
    ..restartAppBetweenScenarios = true
    ..targetAppPath = "test_driver/app.dart";

  return GherkinRunner().execute(config);
}

运行测试

在命令行中运行以下命令：

dart test_driver/app_test.dart

示例代码

以下是完整的示例代码，包括一个简单的计数器应用及其对应的测试：

主应用代码 (lib/main.dart)

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Counter App',
      home: MyHomePage('Counter App Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage(this.title) : super();

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              key: const Key('counter'),
              style: Theme.of(context).textTheme.headline4,
            ),
            FloatingActionButton(
              key: const Key('increment'),
              onPressed: _incrementCounter,
              tooltip: 'Increment',
              child: const Icon(Icons.add),
            ),
          ],
        ),
      ),
    );
  }
}

测试代码 (test_driver/app_test.dart)

import 'dart:async';
import 'package:flutter_gherkin/flutter_gherkin.dart';
import 'package:gherkin/gherkin.dart';
import 'steps/tap_button_n_times_step.dart';

Future<void> main() {
  final config = FlutterTestConfiguration()
    ..features = [RegExp(r'test_driver/features/*.feature')]
    ..reporters = [
      ProgressReporter(),
      TestRunSummaryReporter(),
      JsonReporter(path: './report.json')
    ]
    ..stepDefinitions = [TapButtonNTimesStep()]
    ..restartAppBetweenScenarios = true
    ..targetAppPath = "test_driver/app.dart";

  return GherkinRunner().execute(config);
}

Feature文件 (test_driver/features/counter.feature)

Feature: Counter
  The counter should be incremented when the button is pressed.

  Scenario: Counter increases when the button is pressed
    Given I expect the "counter" to be "0"
    When I tap the "increment" button 10 times
    Then I expect the "counter" to be "10"

步骤定义 (steps/tap_button_n_times_step.dart)

import 'package:flutter_driver/flutter_driver.dart';
import 'package:flutter_gherkin/flutter_gherkin.dart';
import 'package:gherkin/gherkin.dart';

StepDefinitionGeneric TapButtonNTimesStep() {
  return when2<String, int, FlutterWorld>(
    'I tap the {string} button {int} times',
    (key, count, context) async {
      final locator = find.byValueKey(key);
      for (var i = 0; i < count; i++) {
        await FlutterDriverUtils.tap(context.world.driver, locator);
      }
    },
  );
}

通过以上步骤，您可以开始使用 flutter_gherkin 进行行为驱动开发，并确保您的Flutter应用按预期工作。