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sd9today at 9:23 AM1 replyview on HN

I've recently got into red/greed TDD with claude code, and I have to agree that it seems like the right way to go.

As my projects were growing in complexity and scope, I found myself worrying that we were building things that would subtly break other parts of the application. Because of the limited context windows, it was clear that after a certain size, Claude kind of stops understanding how the work you're doing interacts with the rest of the system. Tests help protect against that.

Red/green TDD specifically ensures that the current work is quite focused on the thing that you're actually trying to accomplish, in that you can observe a concrete change in behaviour as a result of the change, with the added benefit of growing the test suite over time.

It's also easier than ever to create comprehensive integration test suites - my most valuable tests are tests that test entire user facing workflows with only UI elements, using a real backend.


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vessenestoday at 9:47 AM

Red/green is especially good with claude because even now with opus 4.6, claude can throw out a little comment like “//Implementation on hold until X/Y/Z: return { true }” and proceed to completely skip implementation based on the inline skip comment for a longgg time. It used to do this aggressively even in the tests, but by and large red/green prompting helps immensely - it tells the agent “think of failing tests as SUCCESS right now” - then you’ll get lots of them.

I’ve always been partial to integration tests too. Hand coding made integration tests feel bad; you’re almost doubling the code output in some cases - especially if you end up needing to mock a bunch of servers. Nowadays that’s cheap, which is super helpful.

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