Python Academy · Lesson

Writing Your First pytest Tests

Understand test discovery, assert statements, and test structure.

Installing pytest

Install pytest with pip. It has no mandatory configuration — it discovers tests automatically.

# pip install pytest

# Run all tests
# pytest

# Run a specific file
# pytest test_math.py

pytest collects any function starting with test_. Use plain assert statements — pytest rewrites them for detailed output.

# test_math.py
def add(a, b):
    return a + b

def test_add():
    assert add(2, 3) == 5

def test_add_negative():
    assert add(-1, 1) == 0