Question

trying to inspect and argument and need to retrieve it. what is the equivalent in Moq? or a way to do it in Moq?

Answer 1

figured it out, utilizing the callback functionality on the Mock Setup

int captured_int;

mocked_obj.Setup(x => x.SomeMethod(It.IsAny<int>()))
    .Callback<int>(x => captured_int = x);

if your method has multiple params

int captured_int;
object captured_object;

mocked_obj.Setup(x => x.SomeMethod(It.IsAny<int>(), It.IsAny<object>()))
    .Callback<int, object>((i, o) => {
                                         captured_int = i;
                                         captured_object = o;
                                     });

then you can do asserts on the captured values;