Testing FastAPI + SQLAlchemy with Real PostgreSQL Fixtures: No More Mocking Misery

📰 Dev.to · Ugur Aslim

Learn to test FastAPI and SQLAlchemy with real PostgreSQL fixtures using Docker and pytest, eliminating mocking misery and catching real migration bugs and transaction edge cases.

intermediate Published 23 May 2026
Action Steps
  1. Set up a Docker container for PostgreSQL using docker-compose
  2. Create pytest fixtures to spin up isolated PostgreSQL databases for each test run
  3. Configure FastAPI and SQLAlchemy to use the pytest fixtures
  4. Write tests using pytest to catch real migration bugs and transaction edge cases
  5. Use Docker and pytest to run tests in an isolated environment
Who Needs to Know This

Backend developers and QA engineers can benefit from this approach to ensure reliable and efficient testing of their FastAPI and SQLAlchemy applications.

Key Insight

💡 Using real PostgreSQL fixtures with Docker and pytest can help catch real migration bugs and transaction edge cases that mocking might hide.

Share This
🚀 Test FastAPI + SQLAlchemy with real PostgreSQL fixtures using Docker and pytest! 🚀

Key Takeaways

Learn to test FastAPI and SQLAlchemy with real PostgreSQL fixtures using Docker and pytest, eliminating mocking misery and catching real migration bugs and transaction edge cases.

Full Article

Title: Testing FastAPI + SQLAlchemy with Real PostgreSQL Fixtures: No More Mocking Misery

URL Source: https://dev.to/uaslimcreate/testing-fastapi-sqlalchemy-with-real-postgresql-fixtures-no-more-mocking-misery-36g7

Published Time: 2026-05-23T09:12:23Z

Markdown Content:
[Skip to content](https://dev.to/uaslimcreate/testing-fastapi-sqlalchemy-with-real-postgresql-fixtures-no-more-mocking-misery-36g7#main-content)

[![Image 1: DEV Community](https://media2.dev.to/dynamic/image/quality=100/https://dev-to-uploads.s3.amazonaws.com/uploads/logos/resized_logo_UQww2soKuUsjaOGNB38o.png)](https://dev.to/)

[Powered by Algolia](https://www.algolia.com/developers/?utm_source=devto&utm_medium=referral)

[Log in](https://dev.to/enter?signup_subforem=1)[Create account](https://dev.to/enter?signup_subforem=1&state=new-user)

## DEV Community

![Image 2](https://assets.dev.to/assets/heart-plus-active-9ea3b22f2bc311281db911d416166c5f430636e76b15cd5df6b3b841d830eefa.svg)0 Add reaction

![Image 3](https://assets.dev.to/assets/sparkle-heart-5f9bee3767e18deb1bb725290cb151c25234768a0e9a2bd39370c382d02920cf.svg)0 Like ![Image 4](https://assets.dev.to/assets/multi-unicorn-b44d6f8c23cdd00964192bedc38af3e82463978aa611b4365bd33a0f1f4f3e97.svg)0 Unicorn ![Image 5](https://assets.dev.to/assets/exploding-head-daceb38d627e6ae9b730f36a1e390fca556a4289d5a41abb2c35068ad3e2c4b5.svg)0 Exploding Head ![Image 6](https://assets.dev.to/assets/raised-hands-74b2099fd66a39f2d7eed9305ee0f4553df0eb7b4f11b01b6b1b499973048fe5.svg)0 Raised Hands ![Image 7](https://assets.dev.to/assets/fire-f60e7a582391810302117f987b22a8ef04a2fe0df7e3258a5f49332df1cec71e.svg)0 Fire

0 Jump to Comments 0 Save Boost

Copy link

Copied to Clipboard

[Share to X](https://twitter.com/intent/tweet?text=%22Testing%20FastAPI%20%2B%20SQLAlchemy%20with%20Real%20PostgreSQL%20Fixtures%3A%20No%20More%20Mocking%20Misery%22%20by%20Ugur%20Aslim%20%23DEVCommunity%20https%3A%2F%2Fdev.to%2Fuaslimcreate%2Ftesting-fastapi-sqlalchemy-with-real-postgresql-fixtures-no-more-mocking-misery-36g7)[Share to LinkedIn](https://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Fdev.to%2Fuaslimcreate%2Ftesting-fastapi-sqlalchemy-with-real-postgresql-fixtures-no-more-mocking-misery-36g7&title=Testing%20FastAPI%20%2B%20SQLAlchemy%20with%20Real%20PostgreSQL%20Fixtures%3A%20No%20More%20Mocking%20Misery&summary=Use%20Docker%20and%20pytest%20fixtures%20to%20spin%20up%20isolated%20PostgreSQL%20databases%20for%20each%20test%20run%2C%20catching%20real%20migration%20bugs%20and%20transaction%20edge%20cases%20that%20mocks%20hide.&source=DEV%20Community)[Share to Facebook](https://www.facebook.com/sharer.php?u=https%3A%2F%2Fdev.to%2Fuaslimcreate%2Ftesting-fastapi-sqlalchemy-with-real-postgresql-fixtures-no-more-mocking-misery-36g7)[Share to Mastodon](https://s2f.kytta.dev/?text=https%3A%2F%2Fdev.to%2Fuaslimcreate%2Ftesting-fastapi-sqlalchemy-with-real-postgresql-fixtures-no-more-mocking-misery-36g7)

[Share Post via...](https://dev.to/uaslimcreate/testing-fastapi-sqlalchemy-with-real-postgresql-fixtures-no-more-mocking-misery-36g7#)[Report Abuse](https://dev.to/report-abuse)

[![Image 8: Ugur Aslim](https://media2.dev.to/dynamic/image/width=50,height=50,fit=cover,gravity=auto,format=auto/https%3A%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3944682%2Fa333519f-9b00-448b-a487-0a2ad077eaf2.jpeg)](https://dev.to/uaslimcreate)

[Ugur Aslim](https://dev.to/uaslimcreate)
Posted on May 23 • Originally published at [uguraslim.com](https://uguraslim.com/blog/testing-fastapi-sqlalchemy-with-real-postgresql-fixtures-no-/)

# Testing FastAPI + SQLAlchemy with Real PostgreSQL Fixtures: No More Mocking Misery

[#fastapi](https://dev.to/t/fastapi)[#sqlalchemy](https://dev.to/t/sqlalchemy)[#postgres](https://dev.to/t/postgres)[#testing](https://dev.to/t/testing)

# [](https://dev.to/uaslimcreate/testing-fastapi-sqlalchemy-with-real-postgresql-fixtures-no-more-mocking-misery-36g7#testing-fastapi-sqlalchemy
Read full article → ← Back to Reads