UNABLE_TO_LOCK_ROW while running two or more tests

Question

I'm trying to run two different test classes, but every time I do this, one of them shows error on the setup method, right in the line where I'm going to insert a new user. Is there a way to fix this? I've checked the depuration logs after executing the tesst, but they don't show anything that could tell where the problem is.

Answer 1

This error during unit tests generally means that a specific record was locked in one test while another tried to use it. Use @isTest(isParallel=false) on each class to force them to run in serial, or use different users (e.g. create a new user) for each test class. Note that these errors won't stop your deployments, as deployments always run tests in serial mode, not parallel mode.