[keycloak-dev] Testing with mocking libraries?

At the moment our testing strategy is only with functional or integration level tests. Both with the full server up and running and primarily testing through public APIs. Now here comes the question should we also allow testing through a mocking library like Mockito? In general I'm against mocking libraries. At best you end up with something that may work, but you're not guaranteed that it actually works. They also have a very big maintenance cost when any changes are made to the codebase. However, take a look at https://github.com/keycloak/keycloak/pull/5215 for example. It is a contribution to add support for the hd param to the Google login. Not sure how else we could test this without a mocking library.