This session explores how to bring unit testing to SQL pipelines using Airflow. I’ll walk through the development of a SQL testing library that allows isolated testing of SQL logic by injecting mock data into base tables. To support this, we built a type system for AWS Glue tables using Pydantic, enabling schema validation and mock data generation. Over time, this type system also powered production data quality checks via a custom Airflow operator. Learn how this approach improves reliability, accelerates development, and scales testing across data workflows.