Flutter状态管理插件getbloc_test的使用

单元测试与testController

testController 创建一个新的特定于 controller 的测试用例，通过给定的 description。testController 将处理断言 controller 在执行 act 后是否按顺序发出 expect 预期的状态。testController 还会确保在评估 expect 之前关闭 controller 流以防止额外的状态被发出。

• build 应该用于所有 controller 的初始化和准备，并且必须返回正在测试的 controller。
• seed 是一个可选函数，它返回一个状态，在调用 act 之前用来填充 controller。
• act 是一个可选回调，它将在测试用例中被调用，并且应该用于与 controller 交互。
• skip 是一个可选整数，可以用来跳过任意数量的状态。默认值为 0。
• wait 是一个可选的 Duration，可以在测试 controller 中的异步操作时使用，例如 debounceTime。
• expect 是一个可选函数，它返回一个 Matcher，用于测试 controller 是否在 act 执行后发出预期的状态。
• verify 是一个可选回调，可以在 expect 之后调用，用于进行额外的验证/断言。verify 调用时会传入由 build 返回的 controller。
• errors 是一个可选函数，它返回一个 Matcher，用于测试 controller 在 act 执行后是否抛出预期的异常。

示例代码

group('CounterController', () {
  testController(
    'emits [] when nothing is added',
    build: () => CounterController(),
    expect: () => [],
  );

  testController(
    'emits [1] when CounterEvent.increment is added',
    build: () => CounterController(),
    act: (controller) => controller.add(CounterEvent.increment),
    expect: () => [1],
  );
});

带有种子状态的示例

testController(
  'CounterController emits [10] when seeded with 9',
  build: () => CounterController(),
  seed: () => 9,
  act: (controller) => controller.increment(),
  expect: () => [10],
);

跳过状态的示例

testController(
  'CounterController emits [2] when CounterEvent.increment is added twice',
  build: () => CounterController(),
  act: (controller) => controller..add(CounterEvent.increment)..add(CounterEvent.increment),
  skip: 1,
  expect: () => [2],
);

等待异步操作的示例

testController(
  'CounterController emits [1] when CounterEvent.increment is added',
  build: () => CounterController(),
  act: (controller) => controller.add(CounterEvent.increment),
  wait: const Duration(milliseconds: 300),
  expect: () => [1],
);

验证内部控制器功能的示例

testController(
  'CounterController emits [1] when CounterEvent.increment is added',
  build: () => CounterController(),
  act: (controller) => controller.add(CounterEvent.increment),
  expect: () => [1],
  verify: (_) {
    verify(() => repository.someMethod(any())).called(1);
  }
);

期望异常的示例

testController(
  'CounterController throws Exception when null is added',
  build: () => CounterController(),
  act: (controller) => controller.add(null),
  errors: () => [isA<Exception>()]
);

注意事项

当使用 testController 与未重写 == 和 hashCode 的状态类时，您可以提供一个匹配器的 Iterable 而不是显式的状态实例。

testController(
  'emits [StateB] when MyEvent is added',
  build: () => MyController(),
  act: (controller) => controller.add(MyEvent()),
  expect: () => [isA<StateB>()],
);

完整示例Demo

以下是一个完整的示例，展示了如何使用 getbloc_test 插件来测试一个简单的计数器控制器。

项目结构

lib/
  main.dart
  counter_page.dart
  counter_controller.dart
  counter_event.dart
  counter_binding.dart

main.dart

import 'package:equatable/equatable.dart';
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:getbloc/getbloc.dart';
import 'package:getbloc_test/getbloc_test.dart';

/// A Mocked Counter Controller
class MockCounterController extends MockController<CounterEvent, int>
    implements CounterController {}

/// A Stub of Counter Event
class FakeCounterEvent extends Fake implements CounterEvent {}

void main() {
  late CounterController counterController;

  setUpAll(() {
    registerFallbackValue<CounterEvent>(FakeCounterEvent());
  });

  setUp(() {
    counterController = Get.put(MockCounterController());
  });

  tearDown(Get.reset);

  testWidgets('renders a counter 5', (WidgetTester tester) async {
    counterController.whenState(5);
    await tester.pumpWidget(GetMaterialApp(home: CounterPage()));
    expect(find.text('5'), findsOneWidget);
  });

  testWidgets('renders a counter 10 and call increment event',
      (WidgetTester tester) async {
    counterController.whenState(10);
    await tester.pumpWidget(GetMaterialApp(home: CounterPage()));
    await tester.tap(find.byTooltip('increment'));
    expect(find.text('10'), findsOneWidget);
    verify(() => counterController.add(Increment())).called(1);
  });

  testWidgets('renders a counter -1 and call decrement event',
      (WidgetTester tester) async {
    counterController.whenState(-1);
    await tester.pumpWidget(GetMaterialApp(home: CounterPage()));
    await tester.tap(find.byTooltip('decrement'));
    expect(find.text('-1'), findsOneWidget);
    verify(() => counterController.add(Decrement())).called(1);
  });
}

counter_page.dart

import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'counter_controller.dart';

/// A [StatelessWidget] which uses:
/// * [get](https://pub.dev/packages/get)
/// * [getbloc](https://pub.dev/packages/getbloc)
/// to manage the state of a counter.
class App extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return GetMaterialApp(
      getPages: [
        GetPage<CounterPage>(
          name: '/',
          page: () => CounterPage(),
          binding: CounterBinding(),
        ),
      ],
    );
  }
}

/// Binding class to connect the page with the controller
class CounterBinding extends Bindings {
  [@override](/user/override)
  void dependencies() {
    Get.lazyPut(() => CounterController());
  }
}

/// A [StatelessWidget] which demonstrates
/// how to consume and interact with a [CounterController].
class CounterPage extends GetView<CounterController> {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Counter')),
      body: controller.obx(
        (counter) => Text(
          '$counter',
          style: Theme.of(context).textTheme.headline1,
        ),
      ),
      floatingActionButton: Row(
        mainAxisAlignment: MainAxisAlignment.end,
        children: _buttons,
      ),
    );
  }

  List<Widget> get _buttons => [
        _getButton(
          Icons.add,
          () => controller.add(Increment()),
          'increment',
        ),
        _getButton(
          Icons.remove,
          () => controller.add(Decrement()),
          'decrement',
        ),
      ];

  Widget _getButton(
          IconData iconData, VoidCallback onPressed, String tooltipText) =>
      Padding(
        padding: const EdgeInsets.all(5.0),
        child: FloatingActionButton(
          tooltip: tooltipText,
          backgroundColor: Get.theme.floatingActionButtonTheme.backgroundColor,
          child: Icon(iconData),
          onPressed: onPressed,
        ),
      );
}

counter_controller.dart

import 'package:get/get.dart';
import 'counter_event.dart';

/// {[@template](/user/template) counter_controller}
/// A simple [Controller] which manages an `int` as its state.
/// {[@endtemplate](/user/endtemplate)}
class CounterController extends Controller<CounterEvent, int> {
  /// {[@macro](/user/macro) counter_controller}
  CounterController() : super(0);

  [@override](/user/override)
  Stream<int> mapEventToState(CounterEvent event) async* {
    if (event is Increment) {
      yield state + 1;
    }
    if (event is Decrement) {
      yield state - 1;
    }
  }
}

counter_event.dart

import 'package:equatable/equatable.dart';

/// {[@template](/user/template) counter_event}
/// Event being processed by [CounterController].
/// {[@endtemplate](/user/endtemplate)}
abstract class CounterEvent extends Equatable {
  /// {[@macro](/user/macro) counter_event}
  const CounterEvent();

  [@override](/user/override)
  List<Object> get props => [];
}

/// Notifies controller to increment state.
class Increment extends CounterEvent {}

/// Notifies controller to decrement state.
class Decrement extends CounterEvent {}