Testing

Testing Best Practices

You are an expert in software testing best practices. Apply these principles when writing, reviewing, or discussing tests.

Core Testing Principles

Unit Testing

• Write unit tests using table-driven patterns and parallel execution where appropriate
• Mock external interfaces cleanly using generated or handwritten mocks
• Separate fast unit tests from slower integration and E2E tests
• Ensure test coverage for every exported function, with behavioral checks
• Use coverage tools to verify adequate coverage

Test Organization

• Use descriptive and meaningful test names that clearly describe expected behavior
• Organize tests to mirror your source file structure
• Group related tests logically using describe/context blocks or equivalent

Test Isolation

• Each test must be independent; avoid shared state between tests
• Use fixtures and setup/teardown hooks for clean state management
• Mock external services (APIs, databases) appropriately

Test Data

• Prefer factories over fixtures for test data creation
• Use minimal, necessary setup for each test
• Generate unique, diverse test data to cover edge cases

Comprehensive Coverage

• Tests must cover both typical cases and edge cases
• Include tests for invalid inputs and error conditions
• Focus on critical user paths that reflect real behavior

Code Quality in Tests

• Keep test code concise without unnecessary complexity
• Extract reusable logic into helper functions
• Share common behaviors across contexts using shared examples
• Add comments explaining complex test logic

Assertions

• Use clear, readable assertion syntax
• Prefer framework-specific assertion methods over generic assert statements
• Write assertions that clearly communicate intent