Why do your tests need a database to check a business rule?
5 min read
The fifth SOLID principle is not about injecting dependencies. It is about something earlier: who writes the contract, and which way the arrow points.
Posts
Notes on building software.
Why does a fake in your tests need twelve methods to use one?
5 min read
The fourth SOLID principle looks at the caller rather than the module you write: nobody should carry methods they never call.
Why does your subclass pass every test and still break production?
5 min read
The third SOLID principle polices something the compiler cannot see: whether the substitute keeps the promises the original made.
Why does every new payment method force you into the same file?
5 min read
The second SOLID principle is not about predicting the future. It asks for something far humbler: leave a socket where you already saw the change arrive.
Why does every change break something you never touched?
5 min read
The first SOLID principle is not about doing one thing. It is about something more useful and stranger: having a single owner.