Mock/Fixture Design

Design test doubles, factories, and fixtures for reliable test infrastructure.

Test Creation Checklist

Mock Object Design

• Define clear interfaces for all mockable dependencies
• Configure mock return values matching realistic production data
• Set up verification for expected interaction counts and order
• Avoid over-mocking by using real implementations where practical
• Ensure mocks fail fast with descriptive error messages

Stub & Fake Implementation

• Create lightweight fake implementations for complex dependencies
• Implement configurable stubs that support multiple test scenarios
• Verify fakes maintain behavioral parity with real implementations
• Provide error simulation modes (network failure, timeout, corruption)
• Keep fake implementations simple and avoid duplicating production logic