public async Task GetUserById() { var contextAccessor = Substitute.For <IHttpContextAccessor>(); var claimsFactory = Substitute.For <IUserClaimsPrincipalFactory <ApplicationUser> >(); var logger = Substitute.For <ILogger <SignInManager <ApplicationUser> > >(); var schemes = Substitute.For <IAuthenticationSchemeProvider>(); var confirmation = Substitute.For <IUserConfirmation <ApplicationUser> >(); var signInManager = Substitute.For <SignInManager <ApplicationUser> >(_userManager, contextAccessor, claimsFactory, _optionsAccessor, logger, schemes, confirmation); var loginValidator = new LoginValidator(signInManager, _userManager); await loginValidator.GetUserById("admin"); await _userManager.Received().FindByNameAsync(Arg.Any <string>()); }