The Engineering Room with Dave Farley Better Software Architecture Thanks To TDD | Steve Freeman In The Engineering Room Ep. 44
17 snips
Apr 5, 2026 
Steve Freeman, software craftsmanship pioneer and co-author of Growing Object-Oriented Software, Guided by Tests, describes the London School of TDD and its role in shaping architecture. They explore mocks as protocol tests, TDD revealing poor design, splitting systems and testing adapters, and why iterative design and the skill of abstraction matter for code habitability and ease of change.
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Smalltalk Shaped Incremental Development
- Smalltalk's live image encouraged fine-grained incremental development and shaped the early XP practices.
- Steve Freeman credits that environment for making rapid, interactive change feel natural and safe for design exploration.
Use Refactoring As Built In Permission
- Treat refactoring as permission to improve design repeatedly rather than a risky one-off task.
- Freeman says baking refactoring into the process gives engineers licence to 'go slower to go faster' and avoid late surprises.
Mocks Model Protocols Not Performance Hacks
- Mocking in the London School is about specifying inter-object protocols, not just speeding tests.
- Freeman warns many misunderstand mocks' intent and that mocking models the messages you expect between components.
