Kotlin Testing

Mocking Without Mockito

In recent years I have grown to like Mockito, everybody’s favourite and invaluable testing helper, less and less. Using a bytecode-twiddling framework to get your code to behave well in tests makes it hard to reason about the tests, and because Mockito (and other mocking frameworks) tend to use a lot of global state to configure the mocks, it’s possible to break test code by refactorings that on “normal” code are totally safe.

I have adopted a different approach for software I develop that does not use Mockito or any other mocking framework but relies on basic JVM features like interfaces and their implementations.