Unit testing with Moq

Question

Let's say I have a plain class with several functions:

public class MyClass
{
    public int GetTotal(int myValue, string myString)
    {
        if (myValue > 10)
            return GetTotal(myValue);
        else
            return GetTotal(myString);
    }

    public int GetTotal(int myValue)
    {
        return myValue * 25 / 12 + 156;
    }

    public int GetTotal(string myString)
    {
        return myString.Length * 25 / 48 + 27;
    }
}

I would like to unit test my first function and "mock" the others, int GetTotal(int myValue) and int GetTotal(string myString), in order to test only the code inside the main function. I am using Moq as the mocking framework. Are there some tricks which would allow me to get the code from the function I want to test and mock the inner call to the other functions? Or should I have to call a second object like this to mock everything?

public class MyCalculator
{
    public int GetTotal(int myValue)
    {
        return myValue * 25 / 12 + 156;
    }

    public int GetTotal(string myString)
    {
        return myString.Length * 25 / 48 + 27;
    }
}

public class MyClass
{
    MyCalculator _Calculator;

    public MyClass(MyCalculator calculator) { _Calculator = calculator; }
    public int GetTotal(int myValue, string myString)
    {
        if (myValue > 10)
            return _Calculator.GetTotal(myValue);
        else
            return _Calculator.GetTotal(myString);
    }
}

I know the latest is the cleanest way, but I have a lot of functions calling themselves one after the other so that would make a lot of classes to write.

Update

Mock implementation of Thomas' answer:

public class MyClass
{
    public int GetTotal(int myValue, string myString)
    {
        if (myValue > 10)
            return GetTotal(myValue);
        else
            return GetTotal(myString);
    }

    public virtual int  GetTotal(int myValue)
    {
        return myValue * 25 / 12 + 156;
    }

    public virtual int GetTotal(string myString)
    {
        return myString.Length * 25 / 48 + 27;
    }
}

[TestClass]
public class Test
{
    [TestMethod]
    public void MyClass_GetTotal()
    {
        Mock<MyClass> myMockedClass = new Mock<MyClass>() {CallBase = true};

        myMockedClass.Setup(x => x.GetTotal(It.IsAny<int>())).Returns(1);
        myMockedClass.Setup(x => x.GetTotal(It.IsAny<string>())).Returns(2);

        var actual = myMockedClass.Object.GetTotal(0,string.Empty);

        Assert.AreEqual(2,actual);
    }
}

Update 2

See Gishu answer also for a more global look on this "issue".

Answer 1

Sure! In Rhino Mocks you can use a partial mock for exactly that purpose. Create a new mock like this:

var mock = MockRepository.GeneratePartialMock<MyClass>();

Then you can mock or stub those two methods that you don't want called like this:

mock.Stub(x => x.GetTotal(10)).Return(42);

It requires your GetTotal methods to be virtual though.