Introduction to Fixtures

What fixtures are and why they replace setup/teardown.

2 min read | pytest

⭐

Want the full learning experience?

Get structured courses, certificates, projects, and instructor support with LabsICT Pro.

Explore Pro Courses

What Are Fixtures?

Fixtures are pytest's answer to setup and teardown. They provide a clean, modular way to prepare test data, set up resources, and clean up after tests finish. Instead of repeating setup code in every test, you define it once in a fixture.

Basic Fixture

A fixture is a function decorated with @pytest.fixture. It can set up data, create objects, or establish connections:

import pytest

@pytest.fixture
def sample_user():
    return {
        "name": "Alice",
        "email": "alice@example.com",
        "age": 30
    }

def test_user_name(sample_user):
    assert sample_user["name"] == "Alice"

def test_user_email(sample_user):
    assert sample_user["email"] == "alice@example.com"

pytest automatically detects that sample_user is a fixture and passes the fixture's return value to the test function.

Why Fixtures Are Better Than Setup

Compare these approaches:

# Without fixtures - repetitive setup
def get_user():
    return {"name": "Alice", "email": "alice@example.com"}

def test_user_name():
    user = get_user()
    assert user["name"] == "Alice"

def test_user_email():
    user = get_user()  # duplicated!
    assert user["email"] == "alice@example.com"

# With fixtures - clean and DRY
@pytest.fixture
def user():
    return {"name": "Alice", "email": "alice@example.com"}

def test_user_name(user):
    assert user["name"] == "Alice"

def test_user_email(user):
    assert user["email"] == "alice@example.com"

Fixture Naming

Fixture names are the parameter names of your test functions. pytest matches them automatically:

@pytest.fixture
def database_connection():
    conn = create_connection()
    yield conn
    conn.close()

# The parameter name MUST match the fixture name
def test_query(database_connection):
    result = database_connection.execute("SELECT 1")
    assert result is not None