Infrastructure as Code, 2nd Edition

Chapter 8. Core Practice: Continuously Test and Deliver

Continuous testing and delivery is the second of the three core practices of Infrastructure as Code, which also include defining everything as code and building small pieces. Testing is a cornerstone of Agile software engineering. Extreme Programming (XP) emphasizes writing tests first with TDD, and frequently integrating code with CI.¹ CD extends this to testing the full production readiness of code as developers work on it, rather than waiting until they finish working on a release.²

If a strong focus on testing creates good results when writing application code, it’s reasonable to expect it to be useful for infrastructure code as well. This chapter explores strategies for testing and delivering infrastructure. It draws heavily on Agile engineering approaches to quality, including TDD, CI, and CD. These practices all build quality into a system by embedding testing into the code-writing process, rather than leaving it to be done later.

This chapter focuses on fundamental challenges and approaches for testing infrastructure. The next chapter (Chapter 9) builds on this one with specific guidance on testing infrastructure stack code, while Chapter 11 discusses testing server configuration code (see “Testing Server Code”).

Why Continuously Test Infrastructure Code?

Testing changes to your infrastructure is clearly a good idea. But the need to build and maintain a suite of test automation code may not be as clear. We often ...