dart-add-unit-test

$27

• Import package:test/test.dart (or package:flutter_test/flutter_test.dart for Flutter).

• Group related tests using the group() function to provide shared context.

• Define individual test cases using the test() function.

• Validate outcomes using the expect() function alongside matchers (e.g., equals(), isTrue, throwsA()).

• Write asynchronous tests using standard async/await syntax. The test runner automatically waits for the Future to complete.

• Manage test setup and teardown using setUp() and tearDown() callbacks.

• If testing code that relies on dependency injection, use package:mockito alongside package:test to generate mock objects, configure fixed scenarios, and verify interactions.

Executing Tests

Select the appropriate test runner based on the project type and test location.

• If working on a pure Dart project, execute tests using the dart test command.

• If working on a Flutter project, execute tests using the flutter test command.

• If running integration tests, explicitly specify the directory path, as the default runner ignores it: dart test integration_test or flutter test integration_test.

Test Implementation Workflow

Follow this sequential workflow when implementing new test suites. Copy the checklist to track your progress.

Task Progress

• 1. Create the test file in the test/ directory, ensuring the _test.dart suffix.

• 2. Import package:test/test.dart and the target library.

• 3. Define a main() function.

• 4. Initialize shared resources or mocks using setUp().

• 5. Write test() cases grouped by functionality using group().

• 6. Execute the test suite using the appropriate CLI command.

• 7. Feedback Loop: Run test -> Review stack trace for failures -> Fix implementation or assertions -> Re-run until passing.

Examples

Standard Unit Test Suite

Demonstrates grouping, setup, synchronous, and asynchronous testing.

import 'package:test/test.dart';

import 'package:my_package/calculator.dart';

void main() {

  group('Calculator', () {

    late Calculator calc;

    setUp(() {

      calc = Calculator();

    });

    test('adds two numbers correctly', () {

      expect(calc.add(2, 3), equals(5));

    });

    test('handles asynchronous operations', () async {

      final result = await calc.fetchRemoteValue();

      expect(result, isNotNull);

      expect(result, greaterThan(0));

    });

  });

}

Mocking with Mockito

Demonstrates configuring a mock object for dependency injection testing.

import 'package:test/test.dart';

import 'package:mockito/mockito.dart';

import 'package:mockito/annotations.dart';

import 'package:my_package/api_client.dart';

import 'package:my_package/data_service.dart';

// Generate the mock using build_runner: dart run build_runner build

@GenerateNiceMocks([MockSpec<ApiClient>()])

import 'data_service_test.mocks.dart';

void main() {

  group('DataService', () {

    late MockApiClient mockApiClient;

    late DataService dataService;

    setUp(() {

      mockApiClient = MockApiClient();

      dataService = DataService(apiClient: mockApiClient);

    });

    test('returns parsed data on successful API call', () async {

      // Configure the mock

      when(mockApiClient.get('/data')).thenAnswer((_) async => '{"id": 1}');

      // Execute the system under test

      final result = await dataService.fetchData();

      // Verify outcomes and interactions

      expect(result.id, equals(1));

      verify(mockApiClient.get('/data')).called(1);

    });

  });

}