Test Containers

Robust Integration Testing

• Source Codegil-air-may/test-containers
• StackPython / FastAPI / TestContiainers / GitHub Actions / Docker

I've put together a small project to show how to set up Testcontainers. This is an interesting topic because many teams struggle with improving code quality. Hopefully, this example can enhance your testing processes.

Checkout the tests/__init__.py file. It contains the special logic to spin up infrastructure containers straight from your codebase.

from testcontainers.mysql import MySqlContainer
from testcontainers.redis import RedisContainer
import sqlalchemy
from config import connections
from scripts.database import seed_utils
from utils import execute_non_query
import json

mysql = MySqlContainer("mysql:5.7.17", port=3306)
mysql.start()
connections["MYSQL"] = mysql.get_connection_url()

engine = sqlalchemy.create_engine(mysql.get_connection_url())
seed_commands = seed_utils.get_seed_commands()

for statement in seed_commands.split(";"):
    execute_non_query(engine, statement)

redis_container = RedisContainer().__enter__()
redis_client = redis_container.get_client()
redis_conn = redis_client.get_connection_kwargs()

redis_client.set(
    1,
    json.dumps(
        {
            "tab_id": 1,
            "table_number": 1,
            "is_paid": 0,
            "items": '[{"name": "chicken_salad", "amount": 1}]',
            "from_day": "2024-05-18",
            "created_at": "2024-05-18T20:36:42",
        },
    ),
)

connections["REDIS"]["host"] = redis_conn["host"]
connections["REDIS"]["port"] = redis_conn["port"]

You can achieve the same behavior using a more elaborate docker-compose.yml. I've also included a GH actions pipeline that works well with this demo.

Just to linger on the topic, "automate everything" should be your mantra for testing. Think of your app as an experiment and build processes that ensure quality results. A solid test suite sets up experiments that give you valuable insights into your system.

Critical logic definitely needs unit tests for specific scenarios, and integration tests should mirror your production environment as closely as possible. This is where Testcontainers shine!