Module-First Development: Designing for Testability and Change

Unit testing and modularity once promised confident change and fearless refactoring. Too often the reality was brittle tests, paralysed teams and slow progress.
Module-First Development (MFD) seeks to restore that promise. It places modules with clear contracts at the centre and directs testing effort where it delivers the most value – at the boundaries of those contracts. MFD is a lightweight framework built on familiar foundations: modularity, encapsulation, unit testing and refactoring. It helps design and test trustworthy modules with strict API contracts, while leaving tools and processes flexible.