#319 increased code coverage above 20%

I don't think so, those mock are more towards UI classes then testing functionality.
Using mockito I can write what I expect from the mocks, using Mk* classes I would need to introduce there additional artificial methods that would be used in one test.
Specifically for my use case I would either way have to create mocks of three additional interfaces (that are not related to my use case), that are used in MkTxn.