Its definitely a bad idea writing new code that builds up on your old code, that has not been tested properly, because you quickly have to start debugging multiple layer is code at once.

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[–] dejected_warp_core@lemmy.world 6 points 17 hours ago (2 children)

Writing the tests first, or at least in tandem with your code, is the only way to fly. It's like publishing a proof along with your code.

it sounds trite: make the tests fit the code. Yes, it's a little more work to accomplish. The key here is that refactors of any scale become trivial to implement when you have unit-test coverage greater than 80%. This lets you extend your code with ease since that usually requires some refactor on some level.

[–] chellomere@lemmy.world 4 points 15 hours ago

This! Also, it's a solid base to stand on when you want to optimize your code. Performing optimizations becomes much easier, quicker and fraught with errors once you have a unit test suite that will instantly tell you whether your change is working or not.

[–] ScintillatingStruthio@programming.dev 1 points 6 hours ago

Writing the tests first also ensures that the test actually fails when you expect it to. I've seen test suites that were silently failing for years because they were (presumably) written after the fact and people just assumed that they tested what they said they did. Went in for some other clean up, stared at the test for 10 minutes wondering "how did this ever pass", and then came to realize that test assertions in Jest inside a forEach apparently don't run in the context of the test and failures won't make the test fail. Changing the forEach to a for...of made it all fail immediately.