Write and organize unit tests for functions, methods, and classes using `package:test`. Use when creating new logic or fixing bugs to ensure code remains correct and regression-free.

Testing Dart and Flutter Applications Contents [Structuring Test Files]( structuring test files) [Writing Tests]( writing tests) [Executing Tests]( executing tests) [Test Implementation Workflow]( test implementation workflow) [Examples]( examples) Structuring Test Files Organize test files to mirror the lib directory structure to maintain predictability. Place all test code within the test directory at the root of the package. Append test.dart to the end of all test file names (e.g., lib/src/utils.dart should be tested in test/src/utils test.dart ). If writing integration tests, place them in an integration test directory at the root of the package. Writing Tests Utilize package:test as the standard testing library for Dart applications. 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. Mocking with Mockito Demonstrates configuring a mock object for dependency injection testing.

dart-add-unit-test