mutation fails on initial test run with jest runner

Question

i'm using strykerjs 5.6.0 with jest runner and react-testing-library. When I run the coverage with jest, all my test pass correctly, but when i run the mutation command (pointing to the same jest config file) i'm getting an error on initial test run because one test is getting a different value than the one i'm getting with the jest command in the coverage.

So, in thispicture it can be seen that the test is not getting the same value, this parseJSONString is a custom method to parse string type props to its js type (due to kill mutants i had to add this), its implementation is this, and it looks like the mutation is returning the fallback instead of the actual value of the array received in the coverage run.

The Stryker config is the following, any ideas? the jest version is the 26.6.3 also. I guess the issue must be related with the react testing library, but i do not understand what could be going on...

Answer 1

I could solve it using the waitFor hook, i don't know why, but stryker needs one render more than jest to get the test case properly mounted.