Question

I have the following method for which I am trying to write a unit test:

using StaticClass;           // writen by some one else, have a dll

namespace Test
{
  Class TestClass
   {
      public void DoSomething(string param1)
      {
         List<string> = StaticClass.GetList(param1)

         // sort the list and do other studd here
      }
  }
}

When I am not sure how to write a test for the DoSomething method, that depends on a static method in another class. The output of that method depends on things like the database on that machine, the environment and few other other factors. So if databases on two machines are different, the same method would give different results. All I know is that GetList returns some value and that method may or maynot have been unit tested by the creator of that class.

How can I test such a method? Is it possible to say something like, whenever StaticClass.Getlist method is called return a custom List<String> that i created in my program? I am writing tests on c#.

Thanks,

Answer 1

Static types with methods that have side-effects are troublesome.

You have two options:

• Short Term: Write an interface which has a GetList method with the right signature. Next write an adapter – a class that implements this interface and delegates to StaticClass internally. Pass an instance of this adapter type into your class as a ctor arg or a method arg. Call GetList on it. You can now use a mocking framework to create a mock object and pass it in your tests and set it up to return canned values.
• Long term: Convert the StaticClass into a non-static one. Pass it in (instead of the adapter object) ; but this requires source code access to StaticClass.