Key differences

unittest

• class-based (unittest.TestCaseunittest.TestCase)
• assertion methods (self.assertEqualself.assertEqual)
• more boilerplate

pytest

• simple functions
• plain assertassert
• powerful fixtures
• rich plugin ecosystem

Example comparison

unittest

import unittest
 
 
def add(a, b):
    return a + b
 
 
class TestAdd(unittest.TestCase):
    def test_add(self):
        self.assertEqual(add(2, 3), 5)

import unittest
 
 
def add(a, b):
    return a + b
 
 
class TestAdd(unittest.TestCase):
    def test_add(self):
        self.assertEqual(add(2, 3), 5)

pytest

 
def add(a, b):
    return a + b
 
 
def test_add():
    assert add(2, 3) == 5

 
def add(a, b):
    return a + b
 
 
def test_add():
    assert add(2, 3) == 5

Why teams like pytest

• less ceremony
• clearer failures
• fixtures scale better than setUp/tearDown
• easy parameterization

🧪 Try It Yourself

Exercise 1 – Write a unittest TestCase

Exercise 2 – assertRaises

Exercise 3 – setUp and tearDown