4 Techniques for Testing Python Command-Line (CLI) Apps

You’ve just finished building your first Python command-line app. Or maybe your second or third. You’ve been learning Python for a while, and now you’re ready to build something bigger and more complex, but still runnable on a command-line. Or you are used to building and testing web applications or desktop apps with a GUI, but now are starting to build CLI applications.

In all these situations and more, you will need to learn and get comfortable with the various methods for testing a Python CLI application.

While the tooling choices can be intimidating, the main thing to keep in mind is that you’re just comparing the outputs your code generates to the outputs you expect. Everything follows from that.

In this tutorial you’ll learn four hands-on techniques for testing Python command-line apps:

  • “Lo-Fi” debugging with print()
  • Using a visual Python debugger
  • Unit testing with pytest and mocks
  • Integration testing