Bill Kocik wrote:
Just to add a couple cents in...
I've been working as either a sysadmin or software developer for the
last 10 years (software development pretty much exclusively for the
last 5 or 6). I started picking up Rails about 2 years ago, and though
I was always aware of TDD - and even occasionally dabbled in it - I
never really embraced it. Not because I didn't see its importance, but
because the barrier to entry always seemed too high, and schedules
never allowed for it (as a friend of mine is fond of saying, "You mean
we don't have time to do it right, but we have time to do it over and
over again?").
Right now I'm working on a personal project for which I have no QA
team to watch my back, so instead I'm doggedly using top-down BDD with
Cucumber (and unit tests) to help keep me in line. I think the biggest
hurdle to learning it is this: Pretty much all the tutorials and docs
written on the topic center around some simple example app that's easy
to test. But in the real world, software is messy, and tends to resist
being tested. I know the traditional counter argument is that this
means your design is flawed, but that isn't always true. One of the
biggest challenges I faced was how to test authentication in my
application, in which users sign in using their Twitter credentials
via OAuth[1]. Another was in testing my own endpoints that create JSON
that's rendered via JS in the browser[2]. Maybe Selenium could have
helped here, but creating tests in general was already slowing me to
the point that I'm a good deal behind schedule, and I couldn't take
another day or so to learn how to use Selenium with the risk that it
might not really suit my situation for one reason or another - because
software is messy.
One that I haven't tackled yet but will have to soon is how to test
code that runs as a BackgrounDRb worker.
I came up with solutions for all of this (except for the BDRb stuff),
but I'm not entirely sure of their quality. They certainly feel
hackish, but I can't put my finger on why. I suspect David Chelimsky
or Ben Mabey or Aslak or any of a hundred or more other people could
have come up with beautiful, elegant solutions
I'm flattered, but FWIW I am always struggling on how best to test
things as well. In cases like you are describing it seems like testing
it is often harder than the actual implementation. Making those tests
valuable without being too brittle can be challenging.
to the challenges I
faced, but since none of them were standing over my shoulder I have no
way of knowing, and none of this is covered in the
write-a-blog-in-10-minutes Rails demo.
That has been my challenge in learning and using BDD.
Thanks for sharing Bill. I totally understand where you are coming
from. IME, it is hard when writing a tutorial or giving a presentation
to not teach to the least common denominator in the audience (the
beginner). Time constraints usually set in too that don't allow you to
do more advanced topics that would require more explanation. Thats why
for most presentations I try to focus more on the process and ideas
rather than the example and tools (i.e stuff you can't learn from a wiki
so easily). I do see your point however. I often feel frustrated in
other presentations at the simplicity of examples given and wish for
more in-depth and challenging examples. Your point is noted: a good
tutorial app for BDD should involve harder to test components (web
services, asynchronous messaging/processing, caching, etc) since this is
what pops up in real projects.
[1] My solution: http://tr.im/oW8y
This is more or less how I would of done this with Cucumber. And you
were complaining about no advanced tutorials. ;) Nice writeup.
[2] I defined these two custom steps (JSON_CALLBACK is defined as the
:callback arg I pass in my 'render :json' calls - but it will trip the
JSON parser if its there):
Then /^I should get valid JSON$/ do
assert_nothing_raised do
assert JSON.parse(@response.body.gsub(/^#{JSON_CALLBACK}\((.*)\)/, '\1'))
end
end
Then /^I should find "(.+)" in JSON/ do |xpath|
json_hash = JSON.parse(@response.body.gsub(/^#{JSON_CALLBACK}\((.*)\)/, '\1'))
xmldoc = Nokogiri::XML(json_hash.to_xml)
xpath.gsub!('_', '-') # in XML, underscores will be dashes.
xpath = "./hash" + xpath unless xpath =~ /^\/\//
assert !xmldoc.xpath(xpath).blank?
end
I probably would of done this in RSpec instead of Cucumber. Then I
would manually tested in a browser.. since you are going to want to do
that anyways. I take this stance quite a bit as I feel adding Selenium
(or another automated browser solution) can potentially add much more of
a maintenance burden than webrat in :rails mode.
Thanks,
Ben
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