basic-usage.rst

Basic Usage

Once a plugin is enabled (e.g., PostgreSQL), you can use its fixtures directly in your tests. The fixture you'll use most often is the Service Fixture (e.g., postgres_service), which provides details about the running database service (host, port, credentials, etc.) so you can connect with your own client.

# Assuming you have installed pytest-databases[postgres] and enabled the plugin.
# Install your preferred PostgreSQL client alongside it: pip install psycopg
import psycopg
from pytest_databases.docker.postgres import PostgresService

def test_connection_with_service_details(postgres_service: PostgresService) -> None:
    conn_str = (
        f"postgresql://{postgres_service.user}:{postgres_service.password}@"
        f"{postgres_service.host}:{postgres_service.port}/{postgres_service.database}"
    )
    with psycopg.connect(conn_str, autocommit=True) as conn, conn.cursor() as cursor:
        cursor.execute("SELECT 1")
        assert cursor.fetchone() == (1,)

def test_write_and_read(postgres_service: PostgresService) -> None:
    conn_str = (
        f"postgresql://{postgres_service.user}:{postgres_service.password}@"
        f"{postgres_service.host}:{postgres_service.port}/{postgres_service.database}"
    )
    with psycopg.connect(conn_str, autocommit=True) as conn, conn.cursor() as cursor:
        cursor.execute("CREATE TABLE IF NOT EXISTS users (id INT PRIMARY KEY, name TEXT);")
        cursor.execute("INSERT INTO users (id, name) VALUES (1, 'Alice');")
        cursor.execute("SELECT name FROM users WHERE id = 1;")
        assert cursor.fetchone() == ("Alice",)