I would like to unit test a method on a class I have made, but this method requires another method to be called first. Example:
// This would work
MyClass myClass1 = new MyClass(mockDevice);
myClass1.Run(myDatastructure);
myClass1.Stop();
// This would throw an InvalidOperationException
MyClass myClass2 = new MyClass(mockDevice);
myClass2.Stop();
Run is starting an operation on a hardware device, and Stop is of course trying to stop that operation (sending a reset-command and starting a timeout-timer).
Anyway I would like to test various post-conditions of calling Stop, but I would like NOT to have to call Run, because I am testing Stop - not Run! I would like something like this:
MyClass myClass = new MyClass(mockDevice);
myClass.Stop();
Assert.IsTrue(mockDevice.ResetCalled);
So far I only see one possible solution, and that is to create a TestableMyClass that inherits from MyClass, that makes it possible to set the right internal state of the MyClass instance before calling Stop. The problem with this solution is that I have to change my MyClass-implementation to have protected members instead of private members, and I don't like the idea of having to change the implementation in order to test it!
Should I use this solution, is there an error in my design, or is there a smarter way of doing this?