How to mock with static methods?

Question

I\'m new to mock objects, but I understand that I need to have my classes implement interfaces in order to mock them.

The problem I\'m having is that in my data acce

Answer 1

A simple solution is to allow to change the static class's implementation via a setter:

class ClassWithStatics {

  private IClassWithStaticsImpl implementation = new DefaultClassWithStaticsImpl();

  // Should only be invoked for testing purposes
  public static void overrideImplementation(IClassWithStaticsImpl implementation) {
     ClassWithStatics.implementation = implementation;
  }

  public static Foo someMethod() {
    return implementation.someMethod();
  }

}

So in the setup of your tests, you call overrideImplementation with some mocked interface. The benefit is that you don't need to change clients of your static class. The downside is that you probably will have a little duplicated code, because you'll have to repeat the methods of the static class and it's implementation. But some times the static methods can use a ligther interface which provide base funcionality.