Letting Claude Code Test Your Backend - Verifying Business Logic via API and SQL

What if an AI agent could test your backend by calling API endpoints and verifying results directly in SQL? I tried exactly that using Claude Code. The agent called API endpoints, inspected a Docker database via SQL, and validated a decision tree of business logic scenarios automatically. When a single operation triggers cascading changes across multiple entities, the number of scenarios grows quickly. In practice, this often ends up with manually clicking endpoints in Postman and checking the database state after every operation. Instead of running tests manually, I wrote down the decision tree of scenarios in a markdown file and handed it to Claude Code. Then I gave it access to a local Docker database and an API service that seeds test data. Claude executed operations through the API, verified the system state using SQL queries, analyzed the results, and reported PASS / FAIL for each scenario. In practice, it behaves like an agent running integration tests — but without writing test