#!/usr/bin/env python3
# -*- coding: utf-8 -*-
class Student(object):
  def __init__(self,name,score):
    self.name = name
    self.score = score
  def get_grade(self):
    if self.score >= 80 and self.score <= 100:
      return 'A'
    elif self.score >= 60 and self.score <= 79:
      return 'B'
    elif self.score >= 0 and self.score <= 59:
      return 'C'
    else:
      raise ValueError('value is not between 0 and 100')

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import unittest
from student import Student
class TestStudent(unittest.TestCase):
  def test_80_to_100(self):
    s1 = Student('Bart',80)
    s2 = Student('Lisa',100)
    self.assertEqual(s1.get_grade(),'A')
    self.assertEqual(s2.get_grade(),'A')
  def test_60_to_80(self):
    s1 = Student('Bart',60)
    s2 = Student('Lisa',79)
    self.assertEqual(s1.get_grade(),'B')
    self.assertEqual(s2.get_grade(),'B')
  def test_0_to_60(self):
    s1 = Student('Bart',0)
    s2 = Student('Lisa',59)
    self.assertEqual(s1.get_grade(),'C')
    self.assertEqual(s2.get_grade(),'C')
  def test_invalid(self):
    s1 = Student('Bart',-1)
    s2 = Student('Lisa',101)
    with self.assertRaises(ValueError):
      s1.get_grade()
    with self.assertRaises(ValueError):
      s2.get_grade()
#运行单元测试
if __name__ == '__main__':
  unittest.main()

if __name__ == '__main__':
  unittest.main()