Why I Prefer Chicago-Style TDD

Short summary

Chicago-style TDD relies on real objects and state assertions, reserving mocks for external boundaries like databases and APIs. Combined with hexagonal architecture, it produces refactor-safe tests that catch real breaks. The core principle: assert on values and observable state, not on internal call patterns.

• •Use real objects for internal domain logic; mock only at system boundaries
• •Tests that assert on state survive refactoring and catch real failures
• •Mocks testing assumptions rather than actual behavior; fakes are a better middle ground

Generated with AI, which can make mistakes.