Because Java. At least I can use an interface to define the function's specification, and then use that in mocks. On the one hand, it seems very different to wh

Because Java. At least I can use an interface to define the function's specification, and then use that in mocks. On the one hand, it seems very different to what I learned about OOP twenty odd years ago, but on the other, it makes for extremely well designed and easy to understand code.