def test_upto_num(self):
     self.assertEqual(
         prime_num(13), [2, 3, 5, 7, 11, 13],
         msg="The result should include n, the argument of the function")
 def test_correct_output(self):
     self.assertEqual(prime_num(15), [2, 3, 5, 7, 11, 13],
                      msg="Return the correct output")
 def test_less_than2(self):
     self.assertEqual(prime_num(1),
                      "0 and 1 are not prime",
                      msg="there exists no prime numbers below 2")
 def test_even_num(self):
     self.assertEquals(
         prime_num(10), [2, 3, 5, 7],
         msg="All even numbers except 2 are not prime numbers")
 def test_negative_num(self):
     self.assertEqual(
         prime_num(-1),
         "invalid input",
         msg="Return invalid input if argument is negative number")