Testing the Layers of Your Application at PyConUK 2016

September 18, 2016 at 07:00 PM

This weekend, I presented at PyConUK 2016, summarizing my recent experiences testing Python webpapps and libraries.

I’ve been writing Python for about 8 years now, mostly on a smaller scale, but the last few years at Yelp have been really interesting to see testing done at a larger scale. Testing has become really important to me, as it helps all the other pieces of your software fit together better.

It was great to be able to share what I’ve learned and brush up on my presentation skills. Unfortunately, I didn’t manage to record a video of the actual presentation, but that was also a lesson learned for when you are presenting.


Testing is a best practice for delivering reliable software, but it can be a hard subject when starting out. What should you test and why? How much testing is enough? So you spent three days and wrote out tests for everything in your module, but was that an effective use of your time?

This talk will give an overview of the different layers that you can write tests for and why you should have them. You start with unit tests, mix in some integration tests, and cover with acceptance tests. Sprinkle with specific testing tools to taste. Tools we’ll discuss include py.test, docker, behave, tox, and coverage. Although the talk focus will be on web apps, the ideas will be relevant to all Python applications.

Writing quality tests is important: flaky tests will cost more time than they save and filler tests that don’t test important areas will weigh you down over time. With stable and effective tests for all layers, you build code you can trust, that you can refactor quickly or change easily without breaking everything. It’s as easy as cake!

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