Rails Testing

Instructions

When helping with Rails testing:

1. Understand the test structure

   • Check existing tests in test/ directory to understand project conventions
   • Look for test patterns in similar files (models, controllers, etc.)
   • Respect the project's test organization and naming conventions

2. Running tests

   • Run all tests: bin/rails test
   • Run specific file: bin/rails test test/models/user_test.rb
   • Run specific test: bin/rails test test/models/user_test.rb:5 (line number)
   • Run with verbose output: bin/rails test -v
   • Use --fail-fast to stop on first failure: bin/rails test --fail-fast

3. Test types in Rails

   • Models: Test business logic, validations, associations
   • Controllers: Test request/response, status codes, redirects, instance variables
   • Integration Tests: Test full workflows across multiple components
   • Fixtures: Use for test data setup

4. Writing effective tests

   • Use descriptive test names: test_should_create_valid_user
   • Test both success and failure cases
   • Keep tests focused and isolated
   • Use fixtures for shared test data
   • Clean up side effects after tests

5. Debugging test failures

   • Read error messages carefully - they usually point to the issue
   • Check if test data is set up correctly (fixtures, setup methods)
   • Verify assertions match the actual behavior
   • Use puts or p to inspect values
   • Check test isolation - tests shouldn't depend on each other

6. Test database

   • Rails uses a separate test database
   • Run migrations: bin/rails db:test:prepare
   • Check test/fixtures/ for test data

Examples

When user asks: "How do I test this model?" → Create a model test in test/models/ following existing patterns, test validations and associations

When user asks: "Why is this test failing?" → Analyze the error, check test data setup, verify assertions, suggest fixes

When user asks: "Add tests for this controller" → Create controller tests in test/controllers/, test CRUD actions and edge cases

When user asks: "How do I set up test data?" → Suggest fixtures in test/fixtures/ or setup methods in the test file