Question

I have a private method like below:

int void SomeMethod(ref string theStr)
{
   // Some Implementation
}

how to write the unit test case for this method.

Answer 1

Seems a bit pointless that a method is void but takes a ref parameter. It would probably make sense to make it return a string:

public class FooBar {
 internal string SomeMethod(ref string theStr) { 
    // Some Implementation 
    return theStr;
 }
}

We also make it internal and specify InternalVisibleTo attribute in AssemblyInfo.cs file:

 [assembly: InternalsVisibleTo("Test.Assembly")]

This way SomeMethod will behave as though it’s internal (i.e. not visible outside its assembly) except for Test.Assembly, which will see it as public.

The unit test is pretty trivial (regardless of whether or not it takes a ref parameter).

[Test]
public void SomeMethodShouldReturnSomething() { 
   Foobar foobar = new Foobar();
   string actual;
   foobar.SomeMethod(ref actual);
   Assert.AreEqual("I'm the test your tests could smell like", actual);
}