Repositories are the abstraction we use to store our data model in Domain Driven Design. Outside DDD, it's the interface between the database and the application.

I've seen a lot of codebases where the database interface isn't properly tested. Most often because it can be difficult to write proper tests for that, and as such it is often skipped.

In this talk I will use Test Driven Development to show how to use mocking frameworks to mock datastores at both the API-, and server-level, and show techniques to test against a real database as well as how we can make the tests more portable by leveraging containers when appropriate.