Inherit Tests Cases

first_grade.py

class FirstGradeMath(object):

    def __init__(self, first_number, second_number):
        self.first_number = first_number
        self.second_number = second_number

    def add(self):
        return self.first_number + self.second_number

    def subtract(self):
        return self.first_number - self.second_number

second_grade.py

import first_grade

class SecondGradeMath(first_grade.FirstGradeMath):

    def multiply(self):
        return self.first_number * self.second_number
        
    def divide(self):
        return self.first_number / self.second_number

test_first_grade.py

import unittest
import first_grade

class FirstGradeMathTests(unittest.TestCase):
    
    def setUp(self):
        self.sut = first_grade.FirstGradeMath(2, 2) 

    def test_addition(self):
        self.assertEqual(4, self.sut.add())

    def test_subtraction(self):
        self.assertEqual(0, self.sut.subtract())

test_second_grade.py

import second_grade
import test_first_grade

class SecondGradeMathTests(test_first_grade.FirstGradeMathTests):

    def setUp(self):
        self.sut = second_grade.SecondGradeMath(2, 2) 

    def test_multiplication(self):
        self.assertEqual(4, self.sut.multiply())
        
    def test_division(self):
        self.assertEqual(1, self.sut.divide())

tests.py

import first_grade
import second_grade
import unittest

class FirstGradeMathTests(unittest.TestCase):
    sut_class = first_grade.FirstGradeMath

    def test_addition(self):
        sut = self.sut_class(2, 2) 
        self.assertEqual(4, sut.add())

    def test_subtraction(self):
        sut = self.sut_class(2, 2) 
        self.assertEqual(0, sut.subtract())

class SecondGradeMathTests(FirstGradeMathTests):
    sut_class = second_grade.SecondGradeMath
    
    def test_multiplication(self):
        sut = self.sut_class(2, 2)
        self.assertEqual(4, sut.multiply())
        
    def test_division(self):
        sut = self.sut_class(2, 2)
        self.assertEqual(1, sut.divide())