Running unit tests on production build?

Question

In one of the projects I am involved with, the team is running a continuous integration/continuous deployment and in development they have a bunch of unit tests as part of the nightly builds.

When this goes to production, they are still running the same tests, every night, even if the code doesn't change and even if they've already been run on dev and then stage.

Does this make sense or should I disable them? The advantage I see is that we have more of identical codebase fordev and production but the downside is the increased load on the server. What do you recommend?

Answer 1

I would only run the tests on a code change, better on each code change and not just in the night. You want to know which code change broke what test.

In your case this would mean when you branch the code to a production version (which is a sort of code change) you run all the tests one more time and that is it. Only when you hot-fix the production code you run the unit tests again. Deploy only versions that have had all tests run successful.

Maybe some tests function as a sort of monitoring of state or database consistency. I cannot find another reason to run them each night. Maintenance scripts should not be hidden in unit-tests though.