#unit test
""" doc string"""
import unittest
from project2.addition import add
A = '7'
B = '5'
C = '0'
D = '0'
class AdditionTestCase(unittest.TestCase):
    """Tests for `addtion.py`"""
    def test_is_valid_input(self):
        """checking for input in codes"""
        self.assertTrue(add(A, B))
    def test_is_valid_input2(self):
        """checking for input in codes"""
        self.assertTrue(add(A, C))
    def test_is_alphabetl(self):
        """testing for alphabets"""
        self.assertFalse(A.islower())
    def test_is_valid_input3(self):
        """testing for normal integers"""
        self.assertFalse(add(C, D))
    def test_is_alphabetu(self):
        """testing for digits"""
        self.assertTrue(A.isdigit())
    def test_is_true(self):
        """testing for the sum"""
        self.assertTrue(add(A, B) == '12')
if __name__ == '__main__':
    unittest.main()

#unit test
""" doc string"""
import unittest
from project2.addition import add
A = '7'
B = '5'
C = '0'
D = '0'
class AdditionTestCase(unittest.TestCase):
    """Tests for `addtion.py`"""
    def test_is_valid_input(self):
        """checking for input in codes"""
        self.assertTrue(add(A, B))
    def test_is_valid_input2(self):
        """checking for input in codes"""
        self.assertTrue(add(A, C))
    def test_is_alphabetl(self):
        """testing for alphabets"""
        self.assertFalse(A.islower())
    def test_is_valid_input3(self):
        """testing for normal integers"""
        self.assertFalse(add(C, D))
    def test_is_alphabetu(self):
        """testing for digits"""
        self.assertTrue(A.isdigit())
    def test_is_true(add(A, B)):
        """testing for the sum"""
        add(A, B).assertTrue('12')
if __name__ == '__main__':
    unittest.main()

Create test_addition.py