xUnitStudy/xUnitStudy.IBll/IStudentBll.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using xUnitStudy.Model;

namespace xUnitStudy.IBll
{
    public interface IStudentBll
    {
        List<Student> Students { get; set; }

        List<Student> GetAll();

        Student GetStudentById(int studentId);

        (bool result, Student student) AddStudent(Student student);

        (bool result, Student student) UpdateStudent(Student student);

        bool DeleteStudent(int userId);

        int GetTuition(int studentId);
    }
}