How can I implement static methods on an interface?

Question

I have a 3rd party C++ DLL that I call from C#.

The methods are static.

I want to abstract it out to do some unit testing so I created an interface with the static methods in it but now my program errors with:

The modifier 'static' is not valid for this item

MyMethod cannot be accessed with an instance reference; qualify it with a type name instead

How can I achieve this abstraction?

My code looks like this

private IInterfaceWithStaticMethods MyInterface;

public MyClass(IInterfaceWithStaticMethods myInterface)
{
  this.MyInterface = myInterface;
}

public void MyMethod()
{
  MyInterface.StaticMethod();
}

Answer 1

Interfaces can't have static members and static methods can not be used as implementation of interface methods.

What you can do is use an explicit interface implementation:

public interface IMyInterface
{
    void MyMethod();
}

public class MyClass : IMyInterface
{
    static void MyMethod()
    {
    }

    void IMyInterface.MyMethod()
    {
        MyClass.MyMethod();
    }
}

Alternatively, you could simply use non-static methods, even if they do not access any instance specific members.