Moq callback method with object parameter

Question

In my scenario I want to mock 1 of the service framework method which takes object parameter and reset it with strongly typed class object.

 public void Updatedata(object pvm)
    {
        var vm = new datamodel()
            {
                name = "test",
                age = 100
            };
        pvm = vm;
    }

It gives compilation error "Invalid callback. Setup on method with parameters (Object) cannot invoke callback with parameters (datamodel)." with below code for mocking.

 mockderived.Setup(p => p.Updatedata(It.IsAny<datamodel>()))
             .Callback<datamodel>(p =>
                 {
                     p.name ="My name is test";
              });

The mock works fine if I change my updatedata method to accepts datamodel as parameter instead of object type. To avoid compilation errors I changed code by passing object as parameter:

  mockderived.Setup(p => p.Updatedata(It.IsAny<object>()))
             .Callback<object>(p =>
                 {
                     p = new datamodel() {name = "My name is test"};
              });

Code get executed by it did not reulted in change of values of datamodel as expected.

What is the expected behavior, the way the method is declared will do nothing to the pvm outside of the object. Did you meant (out object pvm)? — Sunny Milenov
@SunnyMilenov you are right in general approach it should not do anything. Also the updatemethod is part of framework so not aware of exact implementation done there (above I wrote was fake implementation). As i m just writing unit test cases for existing working project so did not thought about it initially. But now even I am feeling confused how it is working without out parameter. — Nitin Agrawal
In framework api, they have used reflection and set properties of the object. It works without using out keyword. — Nitin Agrawal

Nitin Agrawal Nitin Agrawal · Accepted Answer · 2013-06-12T11:00:28

After using reflection to set properties of the object parameter in the callback method, I am able to mock method proerly.

   mockderived.Setup(p => p.Updatedata(It.IsAny<object>()))
             .Callback<object>(p =>
                 {
                     var temp = new datamodel();
                     var t = temp.GetType();
                     var nameprop = "no name";
                     var prop = t.GetProperties();
                     prop[0].SetValue(p, nameprop, null);
              });

Moq callback method with object parameter

1 Answers