How to argument match the generic parameter of a Func<T> with generic constraints?

[cado1982]

Question
Hello. I am trying to mock out this method so that any time it is called the Func is invoked and T is returned.

T New<T>(Func<T> instantiate) where T : Command;

Command is a base class for all of my commands. I thought I could do this

harness.CommandFactory
            .New(Arg.Any<Func<Command>>())
            .Returns(r => r.Arg<Func<Command>>()());

But of course this only matches if the caller passes in the base Command, not a derived class such as AddUserCommand.

Then I came across the newly added Arg.AnyType and thought this was perfect for my needs but I can't get the syntax right. The remark on the method comments seems to indicate that I need to create a derived class but I'm not sure I can for this specific case... "If the generic type parameter has constraints, you will have to create a derived class/struct that implements those constraints." This was the attempt, it fails because now I am back to having a derived type which never matches

public record AnyCommand : Command, Arg.AnyType;

harness.CommandFactory
            .New(Arg.Any<Func<AnyCommand>>())
            .Returns(r => r.Arg<Func<Command>>()());

Does anyone have an idea how/if this can be achieved?

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