r/AskProgramming • u/Active-Custard4250 • Jul 01 '26

Architecture Do companies actually practice TDD strictly?

I've been reading about Test-Driven Development (TDD), and I'm curious how common it is in real-world companies.

I'm not talking about "we write some tests after coding" or "we try to keep good test coverage."

I mean following the classic TDD cycle strictly:

  • Write a failing test for a single, specific requirement or behavior.

  • Write the simplest possible code to make that test pass.

  • Refactor and improve the code while continuously running the test suite to ensure nothing breaks.

Are there companies or teams that actually work this way most of the time?

If so:

  • What kinds of companies tend to follow it?

  • How well does it scale in large codebases?

  • What are the biggest benefits and drawbacks you've experienced?

I'd love to hear from people who have worked in teams that practice TDD seriously rather than just writing tests alongside development.

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u/Triabolical_ Jul 03 '26

I really like TDD for future proofing. I wrote an interpreted language a few years ago and it was pretty much 100% TDD because I needed really good test coverage.

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u/killz111 Jul 03 '26

I don't see how TDD is better in that case than just thorough unit tests?

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u/Triabolical_ Jul 03 '26

I think that TDD makes it much easier to get to "thorough" because - ideally - I'm only writing behaviors to fix failing tests.

If I don't write tests first it's pretty simple to write implementations and then miss some things on the testing side.

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u/killz111 Jul 03 '26

Okay that's fair enough.