this post was submitted on 30 Aug 2023
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How much flakiness do you tolerate in end to end tests? (programming.dev)
submitted 1 year ago* (last edited 1 year ago) by kersplort@programming.dev to c/experienced_devs@programming.dev
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End to end and smoke tests give a really valuable angle on what the app is doing and can warn you about failures before they happen. However, because they're working with a live app and a live database over a live network, they can introduce a lot of flakiness. Beyond just changes to the app, different data in the environment or other issues can cause a smoke test failure.

How do you handle the inherent flakiness of testing against a live app?

When do you run smokes? On every phoenix branch? Pre-prod? Prod only?

Who fixes the issues that the smokes find?

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[–] kersplort@programming.dev 6 points 1 year ago (1 children)

My team has just decided to make working smokes a mandatory part of merging a PR. If the smokes don't work on your branch, it doesn't merge to main. I'm somewhat conflicted - on one hand, we had frequent breaks in the smokes that developers didn't fix, including ones that represented real production issues. On the other, smokes can fail for no reason and are time consuming to run.

We use playwright, running on github actions. The default free tier runner has been awful, and we're moving to larger runners on the platform. We have a retry policy on any smokes that need to run in a step by step order, and we aggressively prune and remove smokes that frequently fail or don't test for real issues.

[–] agressivelyPassive@feddit.de 4 points 1 year ago (1 children)

Shouldn't you find out, why the smoke tests keep failing? It's not a good sign, if you can't even guarantee stability in a controlled environment.

[–] kersplort@programming.dev 2 points 1 year ago (1 children)

It's not a fully controlled environment, that is the point of smokes.

[–] agressivelyPassive@feddit.de 1 points 1 year ago (1 children)

How do you not fully control the environment your PRs are tested in?

[–] kersplort@programming.dev 1 points 1 year ago

dependencies.