public async Task GetStudentIdsWithMatchingEmailShouldReturnStudents()
        {
            var dbOptions = new DbContextOptionsBuilder <ApplicationDbContext>()
                            .UseInMemoryDatabase("test");
            var context = new ApplicationDbContext(dbOptions.Options);

            var roleService     = new WebSchool.Services.RolesService(context);
            var studentsService = new StudentsService(context, roleService);

            var school = new School();
            await context.Schools.AddAsync(school);

            await context.SaveChangesAsync();

            var students = studentsService.GetStudentIdsWithMatchingEmail("email", "12 D", school.Id);

            Assert.That(students.Count == 0);
        }