How to Verify object Type parameters in Moq

Question

I want to test method execution with anonymous parameter, but with known properties.

public interface IToTest
{
   void MethodToTest(object data);
}

This is how I try to achieve this:

Mocker.Mock<IToTest>
   .Verify(x=>x.MethodToTest(
      It.Is<object>(
         obj=>obj.Equals(new { DataProperty = "Test"})
      )),
      Times.Once());

Test is not passing.

I don't want to use

It.IsAny<object>()

because I know expected data.

Answer 1

Your current delegate is testing that the whole object obj is equal to the anonymous type object new { DataProperty = "Test"} - which is unlikely to be testing what you want.

What you need to do is check that:

1) obj has a property with the name you are expecting.

2) that property has a value that you are expecting.

Using reflection you can do both checks with something like the following:

Mocker.Mock<IToTest>
   .Verify(x => x.MethodToTest(
       It.Is<object>(
           obj => 
               obj.GetType().GetProperty("PropertyOne") != null &&
               obj.GetType().GetProperty("PropertyOne").GetValue(obj).ToString() == "Test"
       )),
       Times.Once());

Important note - dont forget the NULL check on result of GetProperty() for cases where the property does not exist.

Answer 2

You will need to use reflection within the delegate to make your comparisons, or use something like FluentAssertions to offload the heavy lifting

for example

//...

var expected = new { 
    DataProperty = "Test" 
    //...known properties
};

Func<object, bool> match = _ => {
    _.Should().BeEquivalentTo(expected);
    return true;
};

Mocker.Mock<IToTest>
    .Verify(x =>
        x.MethodToTest(It.Is<object>(obj => match(obj))),
        Times.Once());

Alternatively, you could have instead capture the object parameter in a callback and just assert the captured argument with fluent assertions.