When I started out in development, unit testing was all the rage. We broke functionality into smaller and smaller classes, building mocks as we went. There was a hidden menace here - one refactoring change would break a slew of tests, and I became disillusioned.

This is when I discovered integration tests - a far more effective safety net for ensuring our system works as expected. But building effective integration tests is much more challenging than isolated unit tests.

In this session, I'll break down the common tools used in integration tests for .NET, including the testing package for Microsoft and other extensions such as FastEndpoints. I'll also cover dealing with shared state and infrastructure like databases using TestContainers, and external uncontrollable dependencies.

Finally, I'll share patterns for building effective and maintainable integration tests for a variety of application types, from web apps, to APIs, to messaging endpoints.