Rhino Mocks changing the body of method during unit test c# - testing

Question

So the problem is as follows. I am unit testing a class SampleClass using Rhino Mocks 3.6. For the tests I use a mock of InnerClass as it is used in the SampleClass constructor. InnerClass has a method called TheMethod(ref string s1,ref string s2). Here is where the problem begins. TheMethod(ref string,ref string) is doing nothing with the parameters and I want TheMethod to actually modify one of the strings (s1). Is it possible, using Rhino Mocks, to do such thing? If so, then how? WhenCalled? Do() handler? I'm clueless. Here's the pseudocode
Class SampleClass
{
Public String SampleClassMethod()
{
string s1 = string.Empty;
string s2 = string.Empty;
string s_final = this.InnerClass.TheMethod(ref s1, ref s2); //TheMethod() which is doing
//nothing with the given strings
if (s_final == "something")
return s1;
}
}
The result is, that s1 is unchanged and for the testing reasons I would like the TestMethod() to modify s1's value WITHOUT changing the body of TheMethod() itself
[TestMethod]
public void TestMethod1()
{
//generating mocks
//SampleClass target; //tested class object
Expect.Call(InnerClassMock.TheMethod(
ref Arg<string>.Ref(Rhino.Mocks.Constraints.Is.Equal(s1), string1).Dummy,
ref Arg<string>.Ref(Rhino.Mocks.Constraints.Is.Equal(s1), string1).Dummy)).IgnoreArguments();
string temp = target.SampleClassMethod();
Assert.AreEqual("1234", temp);
}

Answer 1

Assuming your inner class looks something like this (Note that TheMethod is virtual):
public class SomeClass
{
public virtual string TheMethod(ref string s1, ref string s2)
{
s1 = "X";
s2 = "Y";
return "Z";
}
}
You can use Rhino.Mock's "OutRef" option to define output for ref arguments:
var mock = MockRepository.GenerateStub<SomeClass>();
string temp1 = "", temp2 = "";
mock.Stub(m => m.TheMethod(ref temp1, ref temp2)).OutRef("AAA", "BBB").Return("DEF");
var my1 = "";
var my2 = "";
var result = mock.TheMethod(ref my1, ref my2);
After running this code, my1 will be "AAA", my2 will be "BBB" and result will be "DEF".