Clean architecture and test driven development

A Course of Reso Coder

---

if you are interested in learning clean architecture and TDD, please check this playlist.

As the course was recorded in 2019 and at that time dart did not have null-safety, some things you will need to do in a different way if you are using the Dart version >=2.12 && Flutter version >= 2.0.

For example, when making mocks for unit tests you will need to read the documentations below for a better understanding of what has changed:
Mockito null-safety
Dart null-safety
Flutter unit tests

What's changed in a nutshell

Creating a mock without null-safety - click to see details

creating a mock without null-safety with mockito

class MockClassExample extends Mock implements ClassExample {

}

Creating a mock with null-safety - click to see details

• creating a mock with null-safety
• install build_runner
• create your class_example_test.dart
• inside class_example_test.dart write:

import 'package:flutter_test/flutter_test.dart';
import 'package:mockito/annotations.dart';
import 'package:mockito/mockito.dart';
@GenerateMocks([], customMocks: [
  MockSpec<ClassExampleTest>(
      as: #MockClassExampleTest, returnNullOnMissingStub: false)
])
void main() {}

replace ClassExampleTest and MockClassExampleTest with the object you are going to mock
run flutter pub run build_runner build on your terminal
this will generate the mock file of the object you want to test

After a while, I was having a lot of problems with the unit tests and I decided to change the Mockito for the Mocktail
MockTail Doc

when you are going to implement BLoC and do the unit tests, if you have some problems, I suggest replacing test() with blocTest()
bloc_test details

what changes with bloc_test - click to see details

with test()

        test('Should emit [Error] when the input is invalid', () async {
         
         when(() => mockInputConverter.stringToUnsignedInteger(any()))
             .thenReturn(Left(InvalidInputFailure()));
         
         final expected = [
           Error(errorMessage: INVALID_INPUT_FAILURE_MESSAGE),
         ];
         expectLater(bloc.stream.asBroadcastStream(), emitsInOrder(expected));
        
         bloc.add(GetTriviaForConcreteNumber(numberString: tNumberString));
      });

with blocTest()

blocTest(
        'Should emit [Error] when the input is invalid',
        setUp: () {
          when(() => mockInputConverter.stringToUnsignedInteger(any()))
              .thenReturn(Left(InvalidInputFailure()));
        },
        build: () => NumberTriviaBloc(
          concrete: mockGetConcreteNumberTrivia,
          random: mockGetRandomNumberTrivia,
          inputConverter: mockInputConverter,
        ),
        act: (NumberTriviaBloc bloc) =>
            bloc.add(GetTriviaForConcreteNumber(numberString: tNumberString)),
        expect: () => [
          const Error(errorMessage: INVALID_INPUT_FAILURE_MESSAGE),
        ],
      ); 
      

---

---