Before my holiday I was plagued by invisible differences in doctest output, something like
Set up zope.testing.testrunner.layer.UnitTests in N.NNN seconds. - Ran 2 tests with 0 failures and 0 errors in N.NNN seconds. + Ran 2 tests with 0 failures and 0 errors in N.NNN seconds. ? ++++++++ Tear down zope.testing.testrunner.layer.UnitTests in N.NNN seconds.
After reading some bug reports, I think the following is an accurate summary:
Your operating system’s readline library sometimes emits a
escape code to switch on 8bit character display when initialized.
One of the things needed for the problem to occur: your
variable must be set to
vt100 is fine.
I don’t know why. This is the point at which operating systems can have a
different setting, btw.
import readline somewhere in your python code triggers the output of
the escape code. The escape code is no problem, unless you’re catching
stdout and doing string comparison on it…
The doctest whitespace normalizer doesn’t filter out this escape code.
My hack to work around it is to set the environment variable to something not-xterm-like right smack at the start of my python file that sets up the tests. So something like:
import os # Start dirty hack. os.environ['TERM'] = 'linux' # End of hack.
Not nice. But at least I can continue working for now on my real task. Should doctest’s whitespace normalizer be appended? Is there a real bug somewhere in python’s readline implementation (one bug report mentioned that python before 2.3 didn’t have this problem)? Enlightened opinion is welcome at email@example.com, of course.
Comment by Jean-Paul Ladage: if you use buildout, you can set such an environment variable your the zc.recipe.egg part:
environment-vars = TERM linux
This way you don’t have to hack in the code.
My name is Reinout van Rees and I work a lot with Python (programming language) and Django (website framework). I live in The Netherlands and I'm happily married to Annie van Rees-Kooiman.
Most of my website content is in my weblog. You can keep up to date by subscribing to the automatic feeds (for instance with Google reader):