Can you help me understand Moq Callback?

Question

Using Moq and looked at Callback but I have not been able to find a simple example to understand how to use it.

Do you have a small working snippet whic

Answer 1

There are two types of Callback in Moq. One happens before the call returns; the other happens after the call returns.

var message = "";
mock.Setup(foo => foo.Execute(arg1: "ping", arg2: "pong"))
    .Callback((x, y) =>
    {
        message = "Rally on!";
        Console.WriteLine($"args before returns {x} {y}");
    })
    .Returns(message) // Rally on!
    .Callback((x, y) =>
    {
        message = "Rally over!";
        Console.WriteLine("arg after returns {x} {y}");
    });

In both callbacks, we can:

1. inspect method arguments
2. capture method arguments
3. change contextual state