public void AddUserWithSameUserName() { var newUser = new UserAccount() { UserName = "******", Password = "******" }; try { manger.AddUser("Nasar3", "helloworld123"); Assert.AreNotEqual("Nasar3", newUser.UserName); } catch (Exception error) { var table = Sql.SelectQuery("select * from getuser(@UserName)", newUser); var user = ObjectConverter.ConvertDataTableRowToObject <UserAccount>(table, 0); Sql.AlterDataQuery("delete from useraccount where id = @Id", user); Assert.AreEqual("23505: duplicate key value violates unique constraint \"username\"", error.Message); } }