Database fixture patterns in PyTest

Introduction

Database fixture patterns help set up and clean test data before and after tests run. This keeps tests reliable and repeatable.

When you need to prepare test data in a database before running tests.

When you want to clean up database changes after tests to avoid side effects.

When multiple tests share the same database setup to save time.

When you want to isolate tests so they don't affect each other's data.

Syntax

PyTest

import pytest

@pytest.fixture(scope='function')
def db_setup():
    # Connect to database
    # Insert test data
    yield
    # Clean up test data
    # Close connection

Use @pytest.fixture to create a fixture function.

The scope controls how often the fixture runs (e.g., per function, module).

Examples

This fixture inserts user data before each test and deletes it after.

PyTest

import pytest

@pytest.fixture(scope='function')
def setup_user():
    print('Insert user data')
    yield
    print('Delete user data')

This fixture connects to the database once per module and disconnects after all tests finish.

PyTest

import pytest

@pytest.fixture(scope='module')
def setup_db():
    print('Connect to DB')
    yield
    print('Disconnect from DB')

Sample Program

This test uses the db_setup fixture to prepare and clean test data around the test.

PyTest

import pytest

@pytest.fixture(scope='function')
def db_setup():
    print('Setup: Insert test data')
    yield
    print('Teardown: Remove test data')

def test_example(db_setup):
    print('Running test')
    assert True

Important Notes

Always clean up test data to keep tests independent.

Use yield in fixtures to separate setup and teardown steps.

Choose fixture scope wisely to balance speed and isolation.

Summary

Database fixtures prepare and clean test data automatically.

Fixtures use @pytest.fixture and yield for setup and teardown.

Proper fixture use makes tests reliable and easy to maintain.