Creating and Maintaining Architectural Fitness Functions

on YouTube ↗01h 03m

" summary

Defines architectural fitness functions as measurable rules (a formula) that show how close code is to an architectural goal and gives concrete examples: treat code coverage as an alarm that points to refactoring opportunities, write performance tests as fitness functions to prevent regressions (one feature fixed in sprint 7 reappears by sprint 30 because no perf test existed), and enforce constraints with ArchUnit tests that fail the build (example: detect a vehicle↔engine cycle, move interfaces into a separate module, tests fail then pass in CI).

AI-written summary · about

" chapters (6)

1. 0:00Introduction to fitness functions
2. 12:44What is a fitness function?
3. 28:30Examples of fitness functions
4. 40:15Enforcing architectural constraints
5. 56:28Automating with ArchUnit
6. 1:00:19Continuous integration and Q&A

" related talks

• 42mFitness Functions for Your Architecture – in PracticeThomas Much · Agile meets Architecture Berlin 2023
• 02mInterview with Nathaniel SchuttaNathaniel Schutta · Global Software Architecture Summit 2022
• 50mBuilding Evolutionary ArchitecturesNeal Ford · Craft Conference 2019
• 51mTesting Software ArchitectureMark Richards · Global Software Architecture Summit 2022
• 25mThe Intersection of Fitness Function driven Architecture and Agentic AINeal Ford · AI Native DevCon Fall 2025
• 22mArchitecture & ArchUnitJeremy Cook · ConFoo 2021
• 01h 34mThe Intersection of Architecture and ImplementationMark Richards · Craft Conference 2025
• 39mPrinciples of Evolutionary ArchitectureRebecca Parsons · Codemotion Rome 2016