When should we test our data? From an application development perspective, a unit test against a database isn't a unit test at all. Which makes sense -- connected systems introduce overhead and dependency, both of which reduce stability and decrease productivity during test-driven development (TDD). But if we wait for integration testing, critical functionality can get missed. In this session, we will discuss strategies for filling the data testing gap, directly within a Microsoft SQL Server environment. If you do a lot of work in T-SQL but aren't familiar with TDD, you'll learn the why and how of test-first development. If you're accomplished with unit tests, but never tried them in your database, you'll learn how to apply familiar concepts like setup, mocking, and assertion. We'll spend most of our time walking through a solution based on a real-world project, specifically using the open source tSQLt database unit testing framework.