How to isolate AutoMapper in Unit Tests?

kernel.Bind<IMappingEngine>().ToConstant(Mapper.Engine);

services.AddInstance<IMappingEngine>(Mapper.Engine);

var mockMapper = new Mock<IMappingEngine>();

mockMapper.Setup(mock => mock.Map<TargetType>(It.IsAny<SourceType>())).Returns(targetInstance);

public class User
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public int Age { get; set; }
    }

    public class UserDto
    {
        public int Id { get; set; }
        public string FirstName { get; set; }

    }

    public class Sut
    {
        private readonly IMappingEngine _mapper;

        public Sut(IMappingEngine mapper)
        {
            _mapper = mapper;
        }

        public User Run(UserDto dto)
        {
            return _mapper.Map<User>(dto);
        }
    }

    public class SutTests
    {
        [Fact]
        public void RunShouldReturnUserCorrectly()
        {
            // arrange
            var stubUser = new User();
            var stubUserDto = new UserDto();
            var mockMapper = new Mock<IMappingEngine>();
            mockMapper.Setup(mock => mock.Map<User>(It.Is<UserDto>(stubUserDto))).Returns(stubUser);

            var target = new Sut(mockMapper.Object);

            // act
            var actual = target.Run(stubUserDto);

            // assert
            Assert.AreEquals(stubUser, actual);

        }
    }