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Re: replacing __dict__ with an OrderedDict

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In article <mailman.4488.1325870461.27778.python-list@python.org>,
 Ian Kelly <ian.g.kelly@gmail.com> wrote:

> Randomizing the order is not a bad idea, but you also need to be able
> to run the tests in a consistent order, from a specific random seed.
> In the real world, test conflicts and dependencies do happen, and if
> we observe a failure, make a change, rerun the tests and observe
> success, we need to be able to be sure that we actually fixed the bug,
> and that it didn't pass only because it was run in a different order.

I've seen this argument play out multiple times on this group.  
Executive summary:

OP: "I want to do X"

Peanut Gallery: "You're not supposed to do that"

Here's my commentary on that.

The classic unittest philosophy says that tests should be independent of 
each other, which means they should be able to be run in arbitrary 
order.  Some people advocate that the test framework should 
intentionally randomize the order, to flush out inter-test dependencies 
that the author didn't realize existed (or intend).

Test independence is a good thing.  Many people don't understand this 
when writing tests, and inadvertently write tests that depend on each 
other.  I've worked with those systems.  They're a bear to debug.  
You've got some test suite that runs for 15 minutes and dies at case 37 
of 43.  If you try to run case 37 by itself, it won't run, and you can't 
figure out what state cases 1-36 were supposed to leave the system in to 
make 37 work.  You could sink days or weeks into debugging this kind of 
crap.  BTDT.

That being said, the unittest module, while designed to support the "all 
tests must be independent" philosophy, is a useful piece of software for 
lots of things.  It provides an easy to use framework for writing tests, 
lots of convenient assertions, reporting, test discovery, etc, etc.

If somebody (i.e. the classic "consenting adult" of the Python world) 
wants to take advantage of that to write a test suite where the tests 
*do* depend on each other, and have to be run in a certain order, 
there's nothing wrong with that.  As long as they understand the 
consequences of their actions, don't try to preach unittest religion to 
them.  They're in the best position to know if what they're trying to do 
is the best thing for their particular situation.

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Thread

replacing __dict__ with an OrderedDict Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-01-06 10:48 +0100
  Re: replacing __dict__ with an OrderedDict Lie Ryan <lie.1296@gmail.com> - 2012-01-06 22:43 +1100
    Re: replacing __dict__ with an OrderedDict Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-01-06 14:36 +0100
      Re: replacing __dict__ with an OrderedDict Lie Ryan <lie.1296@gmail.com> - 2012-01-07 04:01 +1100
        Re: replacing __dict__ with an OrderedDict Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-01-07 00:45 +0000
      Re: replacing __dict__ with an OrderedDict Ian Kelly <ian.g.kelly@gmail.com> - 2012-01-06 10:20 -0700
        Re: replacing __dict__ with an OrderedDict Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-01-07 00:49 +0000
          Re: replacing __dict__ with an OrderedDict Lie Ryan <lie.1296@gmail.com> - 2012-01-07 12:21 +1100
          Re: replacing __dict__ with an OrderedDict Ian Kelly <ian.g.kelly@gmail.com> - 2012-01-06 18:24 -0700
            Re: replacing __dict__ with an OrderedDict Eelco <hoogendoorn.eelco@gmail.com> - 2012-01-08 14:03 -0800
              Re: replacing __dict__ with an OrderedDict Lie Ryan <lie.1296@gmail.com> - 2012-01-09 23:10 +1100
                Re: replacing __dict__ with an OrderedDict Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-01-09 14:16 +0100
                Re: replacing __dict__ with an OrderedDict Lie Ryan <lie.1296@gmail.com> - 2012-01-10 23:31 +1100
                Re: replacing __dict__ with an OrderedDict Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-01-10 18:21 +0100
        Re: replacing __dict__ with an OrderedDict Roy Smith <roy@panix.com> - 2012-01-09 09:35 -0500
          Re: replacing __dict__ with an OrderedDict Neil Cerutti <neilc@norwich.edu> - 2012-01-09 14:52 +0000
          Re: replacing __dict__ with an OrderedDict Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-01-09 17:59 +0100
            Re: replacing __dict__ with an OrderedDict Ian Kelly <ian.g.kelly@gmail.com> - 2012-01-09 10:30 -0700
            Re: replacing __dict__ with an OrderedDict Roy Smith <roy@panix.com> - 2012-01-09 20:05 -0500
              Re: replacing __dict__ with an OrderedDict Terry Reedy <tjreedy@udel.edu> - 2012-01-09 23:21 -0500
              Re: replacing __dict__ with an OrderedDict Lie Ryan <lie.1296@gmail.com> - 2012-01-10 23:22 +1100
                Re: replacing __dict__ with an OrderedDict Roy Smith <roy@panix.com> - 2012-01-10 09:05 -0500
                Re: replacing __dict__ with an OrderedDict Lie Ryan <lie.1296@gmail.com> - 2012-01-11 02:57 +1100
                Re: replacing __dict__ with an OrderedDict Roy Smith <roy@panix.com> - 2012-01-10 21:47 -0500
                Re: replacing __dict__ with an OrderedDict Tim Wintle <tim.wintle@teamrubber.com> - 2012-01-10 15:45 +0000
            Re: replacing __dict__ with an OrderedDict Lie Ryan <lie.1296@gmail.com> - 2012-01-10 23:46 +1100
      Re: replacing __dict__ with an OrderedDict Lie Ryan <lie.1296@gmail.com> - 2012-01-07 04:42 +1100
  Re: replacing __dict__ with an OrderedDict Peter Otten <__peter__@web.de> - 2012-01-06 12:44 +0100
    Re: replacing __dict__ with an OrderedDict Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-01-06 14:40 +0100
      Re: replacing __dict__ with an OrderedDict Ian Kelly <ian.g.kelly@gmail.com> - 2012-01-06 09:06 -0700
        Re: replacing __dict__ with an OrderedDict alex23 <wuwei23@gmail.com> - 2012-01-08 20:58 -0800
      Re: replacing __dict__ with an OrderedDict Ian Kelly <ian.g.kelly@gmail.com> - 2012-01-06 09:07 -0700
      Re: replacing __dict__ with an OrderedDict Arnaud Delobelle <arnodel@gmail.com> - 2012-01-06 21:38 +0000
    Re: replacing __dict__ with an OrderedDict Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-01-18 11:29 +0100
  Re: replacing __dict__ with an OrderedDict Ethan Furman <ethan@stoneleaf.us> - 2012-01-06 06:13 -0800
  Re: replacing __dict__ with an OrderedDict Arnaud Delobelle <arnodel@gmail.com> - 2012-01-06 21:32 +0000

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