We have been using prosper from ICF to write our test cases but we stumbled upon situations where the library doesn’t provide necessary elements to write test cases and there are not much contributors to the library as well. We had to now switch to wcm io. Im wondering what people have been using and if wcm io provide everything necessary to write unit tests.
I've been using wcm.io mocks used with the Mockito Test framework for my Unit Tests, and it's working well for me.
On a side note: Check out the best practices for AEM unit test, https://cqdump.wordpress.com/2020/03/30/best-practices-for-aem-unittests/
There are additional article from him which help you to work with Sling Mocks
Hope this helps. There are quite a few articles on the same out there.