Static Methods and Unit Testing

We all know that Interfaces allow us to write loosely-coupled components, and that this "loose-coupledness" comes-in handy during unit testing. Because we can separate the implementation from the method signatures, Interfaces allow us to mock implementations of our dependencies.

Mocking dependencies is important during unit testing because it allows us to isolate the components we are testing from their dependencies -- this means that incorrect behavior from any dependency will not affect the results of our tests.