[Conftest example with fixtures] A Pytest conftest example with a function scoped fixture, with autouse. The code will be executed after every function, since it only has logic after the yield. #python #pytest

conftest.py

"""
This example has not been tested. Use it as a reference only.
"""

import psycopg2
import pytest


USER = "postgres"
PASS = None
HOST = "localhost"
PORT = 5432

DATABASE = "my_schema"
TABLE = "my_table"
CREATE_DB = "CREATE DATABASE %s;"
TRUNCATE = "TRUNCATE TABLE %s CASCADE"
DROP_DB = "DROP DATABASE %s;"


# A simple fixture
def db_conf():
    return dict(user=USER, password=PASS, host=HOST, port=PORT)


# __create_db and _drop_db should come from another package or from a library
def _create_db(configuration):
    connection = psycopg2.connect(**configuration)
    connection.autocommit = True
    try:
        connection.cursor().execute(CREATE_DB, [psycopg2.extensions.AsIs(DATABASE)])
    except Exception as error:
        if not hasattr(error, "pgerror") or "already exists" not in error.pgerror:
            raise error
        print("Database '%s' already exists.", DATABASE)
    connection.close()


def _drop_db(configuration):
    connection = psycopg2.connect(**configuration)
    connection.autocommit = True
    try:
        connection.cursor().execute(DROP_DB, [psycopg2.extensions.AsIs(DATABASE)])
    except Exception as error:
        if not hasattr(error, "pgerror") or "already exists" not in error.pgerror:
            raise error
        print("Database '%s' already exists.", DATABASE)
    connection.close()


@pytest.fixture(scope="session", autouse=True)
def test_db(db_conf):
    """
    This fixture will be executed once in the entire suite, independently of the filters you use
    running pytest. It will create the test_db at the beginning and droping the table at the end
    of all tests.
    """
    _create_db(**db_conf)
    yield
    _drop_db(**db_conf)


# A function scoped fixture
@pytest.fixture(scope="function", autouse=True)
def clear_tables(db_conf):
    """
    This fixture will be executed after every test, clearing the
    given table.
    You can remove the autouse, and specify when it executed whenever you want.
    """

    yield
    connection = psycopg2.connect(**db_conf)
    connection.autocommit = True
    connection.cursor().execute(TRUNCATE, [psycopg2.extensions.AsIs(TABLE)])
    connection.close()