public async Task UpdateStudent_Success()
{
var student = _universityDbContext.Students.Add(new Student()
{
FirstName = "Name", LastName = "Original"
});
_universityDbContext.SaveChanges();
var x = await _studentRepository.ChangeLastName(student.Id, "New");
var updatedStudent = _universityDbContext.Students.AsNoTracking().FirstOrDefault(s => s.Id.Equals(student.Id));
Assert.IsNotNull(updatedStudent);
Assert.AreEqual("New", updatedStudent.LastName);
}