Update integration test to prevent regression

[TWiStErRob]

• Tests Increase visibility of Mockito dependency #498

• Can you back your code up with tests?
• Keep your commits clean: squash your commits if necessary.

I created a separate PR as this might be contested and iterated, and don't want to block the merging of the fix.

[TWiStErRob]

This might be superseded by #502, which a much more robust and realistic way of testing a library.

[TimvdLippe]

Let's do #502 instead indeed!