[TIP] A rare philosophical thought

John Arbash Meinel john at arbash-meinel.com
Fri Aug 1 12:20:11 PDT 2008

Hash: SHA1

Jesse Noller wrote:
> On Fri, Aug 1, 2008 at 3:08 PM, Kumar McMillan <kumar.mcmillan at gmail.com> wrote:
>> On Fri, Aug 1, 2008 at 12:28 PM, C. Titus Brown <ctb at msu.edu> wrote:
>>> """
>>> The Python gurus recommend unit testing to make sure code is solid.
>>> That's great. If I wanted to write dozens of lines of boilerplate
>>> code in order to make sure stuff worked, I'd have stuck with C++. I want
>>> to write less code and be confident in the belief that that code is
>>> correct and error free.
>>> """
>> Whenever I see this kind of resistance I've noticed there is often a
>> misinterpretation of what "automated testing" really means.  I have
>> asked developers who do not write automated tests how they guarantee
>> that a feature works.  The good developers respond with: "well, I add
>> the feature then I fire up the app and verify that it works.  Duh!"
>> This is a great point of entry for helping developers to understand
>> automated testing.  What they are already doing is *the same exact
>> thing* as automated testing except it is manual and not automated.
>> The real problem lies in that it often doesn't make sense to add
>> automated tests.  That is, the app may be too small and manual testing
>> could be as simple as loading up a single page then submitting a form
>> and verifying the success page.  Done.  You've tested your entire app
>> and you know it works.
>> Why automated testing then?  The answer (as we all know) is in
>> scalability.  That's the point to stress when trying to help a
>> developer understand the usefulness of automated testing.  OK, so what
>> happens when you have a sequential form that is 8 pages long?  I.E. to
>> manually test this you have to start at the beginning *every time*.
>> For me, this was exactly when the concept of automated testing
>> clicked.  I had been working on a dating / matchmaking site and the
>> profile signup was indeed about 8 or 10 form pages and there was a
>> very abstract base component that drove every single page of the form.
>>  So if I made a bad change to the base it would break every page of
>> the form in confusing ways.  I developed this app entirely without
>> automated tests and had to test the app by manually going through the
>> form one page at a time!  The result of course was many subtle bugs in
>> the combinations of form elements that I was too lazy to test.
>> But even after a developer understands this concept there is still a
>> problem of discipline.  If you start an app that has 2 pages of forms
>> and that app grows 4 pages of forms then you will probably admit to
>> yourself "OK, I should start writing some tests now."  Unfortunately,
>> for the typical software development team, it is too late to start
>> writing tests at this point.  With typical pressures from the business
>> (MAKE MONEY NOW!) it is almost always too hard to sell the fact that
>> you need to HALT new development for a month while you write automated
>> tests to cover ALL the use cases you have implemented thus far.
>> In conclusion, it is my belief that any app to grow from a prototype
>> into some kind of "stable" tool is doomed to fail if no automated
>> tests exist at that point of maturity.
>> Then again, the value of manual testing should not be underestimated!
>> RE: the original boilerplate argument, don't forget that the average
>> developer writes BAD TESTS.  Especially when you are prototyping an
>> app and you know you *should* write tests but you don't know how the
>> app is going to be implemented this is when you often write a
>> meaningless test.  Instantiating an object is not a very useful test!
>> This type of testing is only going to provide more fuel for the
>> anti-automated-testing developers out there, not to mention give you
>> and your team a sense of false confidence.  To remedy this, I would
>> advise any developer I see who writes these kind of tests to *stop*
>> writing tests for a minute and start manually testing his/her code
>> instead to gain an understanding of what it means to verify a use
>> case.  Even unit testing is about verifying a use case -- you have an
>> object or function [the unit] and another piece of code wants to use
>> it.  Along those lines, doctest provides another great entry point for
>> developers to understand the concept of automated testing.  So the
>> second point is you have to become a "user" to write better tests.
>> Luckily, this is naturally a part of software development.
>> Kumar
>> PS. Don't forget to blame Titus for this rant ;)
> Dang. This is too long to fit on a t-shirt, otherwise I would :)
> -jesse

Automated testing... because manual testing just takes too damn long.

That would fit well, and was certainly where *I* came across automated tests.
(You have to test it anyway, if you can write it down and script it, then you
don't have to remember exactly how you did it the last time.)


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