How to mock HttpContext in ASP.NET Core

I'm trying to mock HttpContext to test my UsersController. The UsersController inherit from

public abstract class ControllerBase

and HttpContext is a property of ControllerBase

public HttpContext HttpContext { get; }

and here is the method in the UsersContoller, which I want to test

 public async Task<IActionResult> Register([FromBody] UserViewModel model)
        {
            _logger.LogDebug("Register new user");

            var user = mapper.Map<User>(model);
            user.Company.Active = false;

            var result = await userManager.CreateAsync(user, model.Password);

            if (result.Succeeded)
            {
                await userManager.AddToRoleAsync(user, Roles.NO_ACCESS);

                //send confirmation email

                string confirmationToken = userManager.GenerateEmailConfirmationTokenAsync(user).Result;

                HostString hostString = HttpContext.Request.Host; //I need to mock httpcontext for this 

                this.mailSender.SendConfirmationMailAsync(user, hostString, confirmationToken);

                return Ok();
            }
            else
            {
                _logger.LogInformation("User could not be registered Errors:");
                result.Errors.ToList().ForEach(e => _logger.LogInformation(e.Description));

                return BadRequest(result.Errors);
            }

        }

this is my BaseTestContoller, in which setup for tests is initialized

[SetUp]
        public void Setup()
        {
            var dbContext = CreateDbContext();

            CreateUserManager();
            CreateMailSender(dbContext);
            CreateMockImapper();
            CreateMockIlogger();
            
            usersController = new Mock<UsersController>(
               userManagerMock.Object,
               new CompanyService(dbContext),
               mailSenderMock,
               new Mock<IConfiguration>().Object,
               iMapperMock.Object,
               iLoggerFactoryMock.Object);

        }

i've tried many options, but it wasn't successful therefor it would be nice if someone could help me. Thanks in advance