Event-driven services - Event Contract and Schema validations

This is to try and check how to test event-driven services using Kafka + Testcontainers, JSON Schema validation, and simple contract assertions.

Prerequisites:

• Docker must be running (Testcontainers will start a Kafka broker).
• Python 3.9+ recommended.

Quick start:

python -m venv .venv
.\.venv\Scripts\activate   # Windows
pip install -r requirements.txt
pytest -q

What it contains:

• Sample schemas/ – JSON Schemas for orders and payments events.
• src/producer.py and src/consumer.py – helpers using kafka-python.
• tests/test_events.py – spins up a Kafka broker with Testcontainers, produces sample events, consumes them and validates with jsonschema.

Docker & Integration Tests

Follow these steps to run the Kafka integration tests locally using Docker.

• Start Docker Desktop (Windows) or ensure Docker daemon is running.

• Start Kafka + Zookeeper (uses the repository docker-compose.yml):

cd C:\SHAN\eda-contract-n-schema-testing
.\scripts\start_kafka.ps1

• Run only the fast, no-Docker tests (default):

C:/SHAN/eda-contract-n-schema-testing/.venv/Scripts/python.exe -m pytest -q

• Run integration tests that require Docker (marked integration):

C:/SHAN/eda-contract-n-schema-testing/.venv/Scripts/python.exe -m pytest -q -m integration

• Stop Kafka + Zookeeper when finished:

.\scripts\stop_kafka.ps1

Notes

• The repo contains three test files:
  • tests/test_events_nodocker.py — unit/contract checks that run without Docker.
  • tests/test_events.py and tests/docker_test_events.py — integration tests marked with integration and skipped automatically if Docker is unavailable. This is just for learning purpose
• If you run integration tests and testcontainers tries to start containers but Docker is not running, the tests will be skipped.