The unittest library has many different assertions but some are more commonly used than others.
Let’s look at how to check for membership, what class a variable is an instance of, and a couple of others.

Membership Assertion

• assertIn(x, y) – Make sure x is a member of y (this is like the in keyword)
• assertNotIn(x, y) – Make sure x is NOT a member of y (this is like the in keyword)
• assertIsInstance(x, y) – Make sure x is an instance of the y class

Dice Example

dice.py

We want to test if a Die is created correctly inside the dice.py script:
http://ref.ghadanfar.com/2018/01/29/dice-py/
A Die instance has a number of sides, and a value that is given to it after it is rolled by the Roll class.
A hand roll can be described via the description variable, where if its value is 3d6 means a hand with 3 dice all having 6 sides.

test.py

Let’s write a test for that:

import unittest 
 
import dice 


class DieTests(unittest.TestCase):
    def setUp(self):
        self.d6 = dice.Die(6)
        self.d8 = dice.Die(8)
        
    def test_creation(self):
        self.assertEqual(self.d6.sides, 6)
        self.assertIn(self.d6.value, range(1, 6))
        
    def test_add(self):
        self.assertIsInstance(self.d6+self.d8, int)


class RollTests(unittest.TestCase):
    def setUp(self):
        self.hand1 = dice.Roll('1d2')
        self.hand3 = dice.Roll('3d6')

    def test_lower(self):
        self.assertGreaterEqual(int(self.hand3), 3)
        
    def test_upper(self):
        self.assertLessEqual(int(self.hand3), 18)
        
    def test_membership(self):
        test_die = dice.Die(2)
        test_die.value = self.hand1.results[0].value
        self.assertIn(test_die, self.hand1.results)
        

Run the test

python -m unittest tests.py