Testing as a poor mans REPL

I quite often find myself not really knowing the exact solution to a problem. When this is the case I often whip up a new test file with just a single test: test().

I use this unnamed test to quickly write up some test data and right there in the test I start working on the implementation of a particularly tricky bit of logic (assuming it’s very isolated and doesn’t have many dependencies).

This way you get a very quick feedback loop because your test data and implementation are literally right next to each other. So when I find my implementation is missing something I can quickly add it, but it also works the other way around. If I discover through writing the implementation that my test data is missing something its straightforward to add a bit of data to verify the implementation.

This is similar to a REPL (read, evaluate, print, loop) but missing some of the convenience. Though with some keyboard shortcuts you get really close.