Many development teams have adopted test-driven development practices for writing application code because of their benefits. Others have turned to containers to package and deploy their software, and it's accepted practice to use automated scripts to build the containers. What we’ve seen few teams do so far is combine the two trends and drive the writing of the container scripts using tests. With frameworks such as Serverspec and Goss, you can express the intended functionality for either isolated or orchestrated containers, with short feedback loops. This means that it’s possible to use the same principles we’ve championed for code by TDD'ing containers. Our initial experience doing so has been very positive.