[Python] How to configure pytest for alembic migrations

I am running a FastAPI application with PostgreSQL database and SQLAlchemy. I used sessionmaker to create and use database sessions, and I have a custom alembic migration script that needs to be performed on the database.

from app.core.config import DATABASE_URL
from app.models import User, Passwords
from app.db import Base

from alembic import context

config = context.config
config.set_main_option('sqlalchemy.url', DATABASE_URL)


fileConfig(config.config_file_name)


target_metadata = Base.metadata



def run_migrations_offline():

url = config.get_main_option("sqlalchemy.url")
context.configure(
url=url,
target_metadata=target_metadata,
literal_binds=True,
dialect_opts={"paramstyle": "named"},
)

with context.begin_transaction():
context.run_migrations()


I want to be able to create a test database, apply the same migration, and teardown after the test. I have tried the following in the conftest.py

# Apply migrations at beginning and end of testing session
@pytest.fixture(scope="session")
def apply_migrations():
warnings.filterwarnings("ignore", category=DeprecationWarning)
environ["TEST"] = "True"
config = Config("alembic.ini")
alembic.command.upgrade(config, "head")
yield
alembic.command.downgrade(config, "base")

@pytest.fixture(scope="session")
def create_test_db():
url = f"{str(DATABASE_URL)}_test"

if database_exists(url):
drop_database(url)
create_database(url)
apply_migrations()
engine = create_engine(url, echo=True)

yield
drop_database(url)


But it does not seem to do anything. I am new to testing and I can't find a decent guide on how to set this up properly. So any kind of help would be greatly appreciated.

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