Pytest Fixtures - Managing Test Dependencies

What is a fixture?

A fixture is a reusable function that provides a value to tests.

Use fixtures for:

test data factories
temporary resources
dependency setup (clients, config)

Basic fixture

test_fixture_basic.py

import pytest
 
 
@pytest.fixture
def user():
    return {"name": "Alice", "role": "admin"}
 
 
def test_user_role(user):
    assert user["role"] == "admin"

test_fixture_basic.py

import pytest
 
 
@pytest.fixture
def user():
    return {"name": "Alice", "role": "admin"}
 
 
def test_user_role(user):
    assert user["role"] == "admin"

Fixture scope

You can control how often fixtures run:

functionfunction (default)
classclass
modulemodule
sessionsession

fixture_scope.py

import pytest
 
 
@pytest.fixture(scope="module")
def expensive_resource():
    return [1, 2, 3]

fixture_scope.py

import pytest
 
 
@pytest.fixture(scope="module")
def expensive_resource():
    return [1, 2, 3]

Yield fixtures (cleanup)

fixture_yield.py

import pytest
 
 
@pytest.fixture
def temp_config_file(tmp_path):
    p = tmp_path / "config.json"
    p.write_text('{"mode": "test"}')
    yield p
    # cleanup happens automatically for tmp_path

fixture_yield.py

import pytest
 
 
@pytest.fixture
def temp_config_file(tmp_path):
    p = tmp_path / "config.json"
    p.write_text('{"mode": "test"}')
    yield p
    # cleanup happens automatically for tmp_path

Pytest Fixtures - Managing Test Dependencies

What is a fixture?

Basic fixture

Fixture scope

Yield fixtures (cleanup)

🧪 Try It Yourself

Exercise 1 – Write a unittest TestCase

Exercise 2 – assertRaises

Exercise 3 – setUp and tearDown

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