Each week in my Tuesday Lunch & Learn livestream, we look at a useful technical skill, define a challenge related to that skill, and solve the challenge live. This week, it's isolating and testing application infrastructure.

Application infrastructure is all the external systems your application interacts with: networks and services; file systems and databases; and global state such as the computer's clock and your application’s process. Without it, your code is a black box. But it’s complicated and difficult to test.

Our challenge this week: build a simple command-line application—and do so in a way that manages the command-line infrastructure well. We need to isolate application from our infrastructure decisions and we need to make sure our infrastructure is tested.

To follow along, download the code from GitHub and check out the 2020-05-12 tag. To see the final result, check out the 2020-05-12-end tag or view it on GitHub.

Visit the Lunch & Learn archive for more.