public static IdentityResult CreateUser <TUser, TKey>(this UserManager <TUser, TKey> manager, TUser user, string password, params string[] roles)
where TUser : class, IUser <TKey>
where TKey : IEquatable <TKey>
{
var result = manager.CreateUser(user, password);
manager.AddUserToRoles(user.Id, roles);
return(result);
}