I’m writing mock unit test code that will Test a class method that downcasts an input argument interface as a concrete class.

Here is the “System Under Test(SUT)” class called CarWrapperFactory:

public class CarWrapperFactory : ICarWrapperFactory
{
    public ICarWrapper CreateCarWrapper(ICarConfigurationWrapper carConfigurationWrapper)
    {
        CarConfiguration loggerConfiguration = ((CarConfigurationWrapper)carConfigurationWrapper).GetCarConfigurationAdaptee();

        return new CarWrapper(carConfiguration.CreateCar());
    }
}

In the aforementioned CarWrapperFactory SUT class, there is downcasting code because it invokes a “protected internal” method called GetCarConfigurationAdaptee.

In my NSubstitute-based Mock Unit Test code, I start off with the following:

ICarConfigurationWrapper carConfigurationWrapperMock = Substitute.For<ICarConfigurationWrapper>();

 // Fill-in-blank code….how to mock the “protected internal” method called GetCarConfigurationAdaptee

ICarWrapperFactory carWrapperFactorySUT = new CarWrapperFactory();

  ICarWrapper carWrapper = carWrapperFactorySUT. CreateCarWrapper(carConfigurationWrapperMock);

Could someone please provide code for the “Fill-in-blank” code above?