Why frozen test fixtures are a problem on large projects and how to avoid them

Re:Why frozen test fixtures are a problem on large projects ... by radanskoric on Tuesday December 09, 2025 @09:38AM (#46205355)

I'm familiar with snapshot testing for UI and I agree with you, they can work really well for this because they're usually quick to verify. And especially if you can build in some smart tolerance to the comparison logic, it can be really easy to maintain.

But how would you do snapshot testing for behaviour? I'm approaching the problem primarily from the backend side and there most tests are about behaviour.

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Re:Why frozen test fixtures are a problem on large projects ... by onionisafruit on Tuesday December 09, 2025 @09:50AM (#46205498)

I'm also primarily on the back end. Like most backenders, I spend my workdays on http endpoints that return json. When I test these the "snapshot" is a json file with a pretty-printed version of the endpoint's response body. Tests fail when the file generated isn't the same as the existing file.

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Re:Why frozen test fixtures are a problem on large projects ... by radanskoric on Tuesday December 09, 2025 @10:01AM (#46205637)

Ah, Ok, yes, for API endpoints it makes a lot of sense. Especially if it's a public API, you need to inspect the output anyway, to ensure that the public contract is not broken.

But, I spend very little or no time on API endpoints since I don't work on projects where the frontend is an SPA. :)

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