I am trying to mock a repository that inherits from the BaseRepository class in the Ardalis.Specification.EntityFrameworkCore library. This base class exposes the ListAsync method which takes in a subclass of the Specification class. This is one of those specifications I have built :

public sealed class SomeSpecification: Specification
{
    public SomeSpecification(Guid someSubEntityID)
    {
        Query
            .Include(p => p.SomeSubEntity)
            .Where(p => p.SomeSubEntity.Id == someSubEntityID)

            .Include(p => p.SomeOtherSubEntity)

            .OrderBy(p => p.SomeProperty);
    }
}

When writing unit tests, I am trying to configure a mock for my ISomeEntityRepository for this specific method using this specification class. What I want is to be able to return a specific collection when this method is passed any SomeSpecification object that was built using a SPECIFIC Guid. As you see, the id that is passed to this constructor is not store anywhere in the class as a property or field when constructing it.

What I CAN do is something like this where the method just returns a specific collection I'm storing in an EntityConstants class when ANY SomeSpecification is passed :

_pfRepoMock.ListAsync(
    Arg.Any(), Arg.Any())
    .Returns(Task.FromResult(EntityConstants.SomeEntityCollection()));

This works fine but I'm not able to return 2 different collections depending on what Guid was passed to the SomeSpecification constructor. In my ideal world (lol) what I'd like to be able to do is something like this :

_pfRepoMock.ListAsync(
    Arg.Any().ConstructedWith(EntityConstants.SomeID), Arg.Any())
    .Returns(Task.FromResult(EntityConstants.SomeEntityCollection()));

_pfRepoMock.ListAsync(
    Arg.Any().ConstructedWith(EntityConstants.SomeOtherID), Arg.Any())
    .Returns(Task.FromResult(EntityConstants.SomeDifferentEntityCollection()));

I know there is an NSubstitute.Equivalency library that adds an ArgEx class but I can't see how it can accomplish what I want.

How can I achieve this?