using System;

using NSubstitute;

using NUnit.Framework;

​

public class XOptions

{

    public bool IsSet { get; set; }

}

​

​

public interface IDoSomething

{

    void DoIt(Action<XOptions> options);

}

​

​

[TestFixture]

public class TestSample

{

    [Test]

    public void DoIt_Tests()

    {

        // Arrange 

        var dosomething = Substitute.For<IDoSomething>();

        // Action

        dosomething.DoIt(o => o.IsSet = true);

        // Assert

        dosomething.Received(1).DoIt(Arg.Any<Action<XOptions>>()); // OK

        dosomething.Received(1).DoIt(o => o.IsSet = true); // Fail

    }

}