Question

I have the following code

public ClassToTest : IClassToTest
{
    private readonly DBRepository rep;

    public bool MethodA()
    {
        //Some logic
        var result=MethodB();
        //Do some logic against result;
    }
    public ResultType MethodB()
    {
        return Rep.GetResult();
    }
}

If I want to Unit testing MethodA, what is the best practice to test the interaction between MethodA and MethodB? I am thinking to test MethodA like testing MethodB by mocking Database dependency Rep, just like MethodA has the following implementation

    public bool MethodA()
    {
        //Some logic
        var result=Rep.GetResult();
        //Do some logic against result;
    }

But it is not intuitive by checking the logic in the code and the test method. I am looking for a solution similar to the one mentioned here for Java.

unit testing composite service methods

But It is not working for C#.

One extra question, What if MethodB is private, does it make any difference for the Unit testing strategy?

Update: prefer not to change the structure of the class. like not making MethodB as virtual or Move the MethodB out of the class into another test

Thanks in advance.

Answer 1

You don’t want to test the interaction between MethodA and MethodB, you want to test that MethodA will return the expected bool result, given some context.

The fact that MethodA calls MethodB is not germaine to this test; but the fact that Rep.GetResult() will at some point be called is.

As you mentioned, you can mock the dependency Rep, so it won’t matter whether MethodB is public or private.

1. Mock and inject the dependency
2. Call MethodA
3. Assert against the result