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

Here's an example of using a callback to test an entity sent to a Data Service that handles an insert.

var mock = new Mock();
DataEntity insertedEntity = null;

mock.Setup(x => x.Insert(It.IsAny())).Returns(1) 
           .Callback((DataEntity de) => insertedEntity = de);

Alternative generic method syntax:

mock.Setup(x => x.Insert(It.IsAny())).Returns(1) 
           .Callback(de => insertedEntity = de);

Then you can test something like

Assert.AreEqual("test", insertedEntity.Description, "Wrong Description");