First time using TDD

Palindrome.py

class Palindrome(object):
    def is_palindrome(self, palindrome):

        if not isinstance(palindrome, str):
            return False

        # Define all variables
        lower_case_palindrome = palindrome.lower().replace(' ', '').replace(',', '').replace('.', '')
        reversed_palindrome = self.reverse_palindrome(lower_case_palindrome)

        if reversed_palindrome == lower_case_palindrome:
            return True

        return False

    def reverse_palindrome(self, palindrome):

        # Cast the input into an array, and reverse the elements
        reversed_palindrome = list(reversed(palindrome))

        reversed_palindrome = "".join(reversed_palindrome)
        reversed_palindrome = reversed_palindrome.replace(' ', '')

        return reversed_palindrome

    def create_palindrome(self, palindrome):
        if not isinstance(palindrome, str):
            return None

        if self.is_palindrome(palindrome):
            return palindrome

        # Join the original input with the reversed input
        created_palindrome = palindrome + "".join(list(reversed(palindrome)))

        return created_palindrome

testPalindrome.py

import unittest

from Palindrome import Palindrome


class TestPalindrome(unittest.TestCase):
    def test_palindrome_can_be_instantiated(self):
        self.assertIsInstance(Palindrome(), Palindrome().__class__)

    def test_palindrome_will_return_true_if_nothing_is_put_in(self):
        self.assertTrue(Palindrome().is_palindrome(''))

    def test_palindrome_will_return_false_if_array_is_put_in(self):
        self.assertFalse(Palindrome().is_palindrome([]))

    def test_palindrome_will_return_false_if_none_is_put_in(self):
        self.assertFalse(Palindrome().is_palindrome(None))

    def test_palindrome_will_return_false_if_acdefg_is_put_in(self):
        self.assertFalse(Palindrome().is_palindrome('abcdefg'))

    def test_palindrome_will_return_true_if_abba_is_put_in(self):
        self.assertTrue(Palindrome().is_palindrome('abba'))

    def test_palindrome_will_return_true_if_a_santa_at_nasa_is_put_in(self):
        self.assertTrue(Palindrome().is_palindrome('A Santa at Nasa'))

    def test_palindrome_will_return_true_if_a_car_a_man_a_maraca_is_put_in(self):
        self.assertTrue(Palindrome().is_palindrome('A car, a man, a maraca'))

    def test_palindrome_will_return_nothing_if_nothing_is_put_into_create(self):
        self.assertIs(Palindrome().create_palindrome(''), '')

    def test_palindrome_will_return_none_if_empty_array_is_put_into_create(self):
        self.assertIsNone(Palindrome().create_palindrome([]))

    def test_palindrome_will_return_none_if_none_is_put_into_create(self):
        self.assertIsNone(Palindrome().create_palindrome(None))

    def test_palindrome_will_return_abccba_if_acb_is_put_into_create(self):
        self.assertEqual(Palindrome().create_palindrome('abc'), 'abccba')

    def test_palindrome_will_return_abba_if_abba_is_put_into_create(self):
        self.assertEqual(Palindrome().create_palindrome('abba'), 'abba')

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