Jeremy Satterfield
Coding, Brewing and Tulsa Life

Viewing posts tagged testing

Unit Testing Recursion in Python

Today I finally figured out the solution to a problem I've been trying to solve for a while. It's kind of hacky and maybe a bad idea, but now I know it's possible. The problem has always been that I'd like to test that a function recurses, but not needing it to actually have the recursion execute within to test. Just a unit test to assert that recursion is happening. After a little thought about how Python stores references I came up with this.

Keeping MRO In Mind When Mocking Inherited Methods

So I just spent a couple of hours banging my head on a ridiculous PyMox mocking issue and though I'd share. Here is an example of the existing code.

Mocking a property in Python

Anytime I see someone turning an instance method into a property on a Python object, I always have to step back and rethink whether it's really the right thing to do. While properties certain have valid use cases, I often see them overused and misused. This can result in code that is harder to refactor should you decide you actually do want to accept arguments as well as less straight forward to separate in unit tests.

Mocking Python's built-in open function

A while back I was working on my podcast client and ran into an issue downloading large files. The root problem was that all of Django's FileField backends store the file (or file-like object) to memory then saves it to disk, and the cubieboard system I was using had limitied memry resources, resulting in "out of memory" errors. After much searching and hacking I finally settled on just storing the file to disk myself using requests streaming argument. This allowed me to download the file in chunks and save directly to disk and then tell the Django field where I placed it, as you can see here.

Using Tox with Travis CI to Test Django Apps

Being a fan of good testing, I'm always trying to find ways to improve testing on various projects. Travis CI and Coveralls are really nice ways to set up continuous integration for your open-source projects. A couple months ago I finally started hearing grumblings about tox and how everyone was it using for their Python test automation. Every time I'd try to wrap my head around it, something always eluded me, so this week I finally decided to dive in head first and see if I could get to the bottom of it and how it could improve my current integration setup.