Skip to main content

Testing In Python...and my Two cents

The only lesson I have learned in mys past one and half of years of experience in testing is that the easier I make writing and running tests for my programs, the faster I can produce bug-free software.

Being a developer and also being a tester can do wonders I think. Never before this thought would have crossed my mind while coding.

That is why I start most projects nowadays with two pre-baked files: and
With this setup and tools like Nose, testing code in Python for me is nearly pain free. Recently however, I notice one aspect of the unittest package in Python's standard libary drives me absolutely crazy:
Why is there no simple method to run a single test case from within an interactive python shell?
As developers, this is important because if we are going to make writing tests an integral part of our development workflow, one needs some way to actually run the damn test without dropping out of our Python sessions and breaking out of our mental flow.
Being forced to run tests solely from the commandline also means we can't take advantage of features like ipython's ability to automatically drop into a pdb debugging session when an error occurs. This is extremely useful for when you want to introspect one or two variables to determine why a test failure occurred.
In general, it seems like the unittest library's lack of a simple function to run single test cases in an interactive shell dis-incentivizes programmers from writing tests and detracts from python's whole "rapid iteration" ethos.
After googling around and failing to find any good alternatives, I've finally settled on writing my own utility function to run single test cases:

def runtest(testCase, methodName):
    """ Runs a test case from within interactive shell """

    tc = testCase(methodName)
    getattr(tc, "setUp", lambda:None)()
        getattr(tc, methodName)()  
        getattr(tc, "tearDown", lambda:None)()

I add this function to every single project that I create now, and the qualitative feel of writing tests just feels so much more natural now. I also find myself writing more tests and running them more often with this function in my projects.
Give it a try, and let me know whether this has any effect for you. I'd love to hear your feedback on how it affects your development workflow.

Popular posts from this blog

LibrePlanet 2017: Liberating your open source experience

LibrePlanet is a yearly gathering of free software activists, users, and contributors—and, it's my favorite conference of the year. Here's why.
LibrePlanet is run by the Free Software Foundation, and has steadily evolved from a yearly members' meeting with presentations from staff and board members to a full blown two-day conference with speakers and attendees from all over the world. The event brings people who care about free software together to talk about the future of the movement, address current challenges, and celebrate successes.
Prelude I was invited to give a talk at LibrePlanet 2017 on 25th March at MIT, in Cambridge, Massachusetts representing Mozilla as a Tech Speaker. I reached Boston on 25th early morning. Around 1 AM. The journey itself was awesome till I realized that you don't get Uber or Lyft at Boston Airport.

Not that the apps don't function there. They work! Just no driver will be ready to pick you up from Airport at that time. After trying t…

Maximum Call Stack size exceeded: My mishap with nodejs and MongoDB

Working with nodejs is always an adventure and mix MongoDB with it, and it becomes very interesting for a nodejs enthusiast like me.

While working on a pet project involving Native MongoDb driver and nodejs I encountered a weird problem.

RangeError:MaximumcallstacksizeexceededAs usual my first thought was to Google out what I was facing and googling it out led me to the following to links.RangeError: Maximum call stack size exceededCalling RangeError: Maximum call stack size exceeded Also In some posts in MongoDB’s forum I saw that peoples said saving in `process.nextTick` or wrapping the call function in `parseInt` will also fix the problem, but it most certainly didn't work for me.So I started digging in on my own and soon enough found the reason.

If you’re trying to save a document and saving process somehow exited with an RangeError: Maximum call stack size exceeded exception, it’s related to what you want to save in the database. I had this problem a…

All Hands 2016: MozLondon, A recount

I recently had the opportunity to take part in Mozilla All Hands 2016 (a.k.a #MozLondon). Mozilla All hands. All Hands are bi-yearly events of Mozilla where all the paid staff from different teams around the globe meet with each other along with a handful of invited volunteers to disscuss about future projects and get some work done! This year it was in London and just immediately before Brexit (I actually didn't even know about it before I went there). It was a work week, so essentially the event spanned from Monday to Friday. I arrived at LHR on Monday morning, and then there was the awesome Heathrow Express which took me to Paddington, just a 7 mins walk away from Hilton Metropole where I was staying with a bunch of other people. The event started with all of us having an evening orientation familiarizing us with rules and regulations along with Code of Conduct(that turned out to be really important later on...).  Tuesday started with a Planery. Which you can see if you are lo…