Hacker News Reader

Great article! I've found myself going through the same cycle of getting something working in the REPL and then regretting not having tests some time in the future several times!

In my experience much of the value of unit tests comes from "proofs of correctness", which REPL-driven development also provides! But unit tests also provide a lot of value in making confidence in changes, and knowing that the behaviour your verified in your REPL stays correct weeks and months later.

I'm guessing TDD stands for Test Driven Design/Development, but I feel compelled to call out the author's failure to spell out the acronym at its first usage. Same for Read Eval Print Loop.

I guess it's understandable for Uncle Bob to omit those - he's been chewing on the subject of TDD for many years now, and REPLs are his recent darling.

Why not both? After I am done experimenting with the REPL in a playground, I clean it up and put it in a test.

REPL Driven Design