Přeskočit na obsah

Testing

Tento obsah zatím není dostupný ve vašem jazyce.

Bloc was designed to be extremely easy to test. In this section, we’ll walk through how to unit test a bloc.

For the sake of simplicity, let’s write tests for the CounterBloc we created in Core Concepts.

To recap, the CounterBloc implementation looks like:

counter_bloc.dart
sealed class CounterEvent {}
final class CounterIncrementPressed extends CounterEvent {}
final class CounterDecrementPressed extends CounterEvent {}
class CounterBloc extends Bloc<CounterEvent, int> {
CounterBloc() : super(0) {
on<CounterIncrementPressed>((event, emit) => emit(state + 1));
on<CounterDecrementPressed>((event, emit) => emit(state - 1));
}
}

Setup

Before we start writing our tests we’re going to need to add a testing framework to our dependencies.

We need to add test and bloc_test to our project.

Terminal window
dart pub add dev:test dev:bloc_test

Testing

Let’s get started by creating the file for our CounterBloc Tests, counter_bloc_test.dart and importing the test package.

counter_bloc_test.dart
import 'package:test/test.dart';
import 'package:bloc_test/bloc_test.dart';

Next, we need to create our main as well as our test group.

counter_bloc_test.dart
void main() {
group(CounterBloc, () {
});
}

Let’s start by creating an instance of our CounterBloc which will be used across all of our tests.

counter_bloc_test.dart
group(CounterBloc, () {
late CounterBloc counterBloc;
setUp(() {
counterBloc = CounterBloc();
});
});

Now we can start writing our individual tests.

counter_bloc_test.dart
group(CounterBloc, () {
late CounterBloc counterBloc;
setUp(() {
counterBloc = CounterBloc();
});
test('initial state is 0', () {
expect(counterBloc.state, equals(0));
});
});

At this point we should have our first passing test! Now let’s write a more complex test using the bloc_test package.

counter_bloc_test.dart
blocTest(
'emits [1] when CounterIncrementPressed is added',
build: () => counterBloc,
act: (bloc) => bloc.add(CounterIncrementPressed()),
expect: () => [1],
);
blocTest(
'emits [-1] when CounterDecrementPressed is added',
build: () => counterBloc,
act: (bloc) => bloc.add(CounterDecrementPressed()),
expect: () => [-1],
);

We should be able to run the tests and see that all are passing.

That’s all there is to it, testing should be a breeze and we should feel confident when making changes and refactoring our code.

You can refer to the Weather App for an example of a fully tested application.