minitest-coder

Minitest tests for Rails applications use either Traditional or Spec style syntax to verify behavior. Write tests organized by unit, service, and integration scopes, applying the AAA structure: arrange test data and mocks, act on the code under test, and assert the expected outcome. Rails integration tests can verify controller actions, model validations, and database interactions.

Traditional Minitest uses class-based tests with methods prefixed by test_, while Spec style uses describe blocks with it assertions for more readable, BDD-focused syntax. Both styles support the same assertions, fixtures, and mocking patterns; the choice depends on team preference and existing codebase conventions.

Fixtures provide reusable test data loaded before each test runs, reducing setup code. Mocks replace external dependencies or slow operations to isolate the code being tested. Minitest supports both through fixture files in test/fixtures and built-in stubbing and mocking methods that verify interactions without touching the actual resource.

Yes, Minitest supports unit tests for models and services, controller integration tests for request-response flows, and service layer tests for business logic. Organize tests by scope, use fixtures for model data, mock external calls, and apply the AAA pattern to ensure each test has a single responsibility and runs fast.

Tests that minimize database interactions run faster and are less flaky because they avoid I/O latency and concurrency issues. Use fixtures for read-only data, mock associations and external services, and employ in-memory assertions where possible. This approach keeps your test suite performant while maintaining comprehensive coverage of happy paths and edge cases.

Write test names that clearly describe what behavior is being verified, such as test_valid_email_is_accepted or test_raises_error_when_price_is_negative. Structure each test with AAA, cover both happy paths and edge cases, and use assertions that fail with meaningful messages. This approach makes tests self-documenting and easier to debug when they fail.