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Groups > comp.lang.python > #22389

Re: unittest: assertRaises() with an instance instead of a type

Date 2012-03-30 10:45 -0700
From Ethan Furman <ethan@stoneleaf.us>
Subject Re: unittest: assertRaises() with an instance instead of a type
References <pncb49-ur7.ln1@satorlaser.homedns.org> <4f735345$0$29981$c3e8da3$5496439d@news.astraweb.com> <eced49-sge.ln1@satorlaser.homedns.org> <4f751e31$0$29981$c3e8da3$5496439d@news.astraweb.com>
Newsgroups comp.lang.python
Message-ID <mailman.1153.1333132489.3037.python-list@python.org> (permalink)

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Steven D'Aprano wrote:
> To the degree that the decision of how finely to slice tests is a matter 
> of personal judgement and/or taste, I was wrong to say "that is not the 
> right way". I should have said "that is not how I would do that test".
> 
> I believe that a single test is too coarse, and three or more tests is 
> too fine, but two tests is just right. Let me explain how I come to that 
> judgement.
> 
> If you take a test-driven development approach, the right way to test 
> this is to write testFooWillFail once you decide that foo() should raise 
> MyException but before foo() actually does so. You would write the test, 
> the test would fail, and you would fix foo() to ensure it raises the 
> exception. Then you leave the now passing test in place to detect 
> regressions.
> 
> Then you do the same for the errorcode. Hence two tests.

[snip]

> So: never remove tests just because they are redundant. Only remove them 
> when they are obsolete due to changes in the code being tested.

Very persuasive argument -- I now find myself disposed to writing two 
tests (not three, nor five ;).

~Ethan~

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Thread

unittest: assertRaises() with an instance instead of a type Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-28 14:28 +0200
  Re: unittest: assertRaises() with an instance instead of a type Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-28 18:07 +0000
    Re: unittest: assertRaises() with an instance instead of a type Ben Finney <ben+python@benfinney.id.au> - 2012-03-29 12:55 +1100
      Re: unittest: assertRaises() with an instance instead of a type Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-29 06:35 +0000
      Re: unittest: assertRaises() with an instance instead of a type Peter Otten <__peter__@web.de> - 2012-03-29 08:55 +0200
      Re: unittest: assertRaises() with an instance instead of a type Steve Howell <showell30@yahoo.com> - 2012-03-28 22:50 -0700
    Re: unittest: assertRaises() with an instance instead of a type Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-29 09:08 +0200
      Re: unittest: assertRaises() with an instance instead of a type Peter Otten <__peter__@web.de> - 2012-03-29 09:48 +0200
      Re: unittest: assertRaises() with an instance instead of a type Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-30 02:45 +0000
        Re: unittest: assertRaises() with an instance instead of a type Ethan Furman <ethan@stoneleaf.us> - 2012-03-30 10:45 -0700
    Re: unittest: assertRaises() with an instance instead of a type Ethan Furman <ethan@stoneleaf.us> - 2012-03-29 08:35 -0700
      Re: unittest: assertRaises() with an instance instead of a type Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-30 02:53 +0000
  Re: unittest: assertRaises() with an instance instead of a type Terry Reedy <tjreedy@udel.edu> - 2012-03-28 14:26 -0400
    Re: unittest: assertRaises() with an instance instead of a type Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-29 09:28 +0200
      Re: unittest: assertRaises() with an instance instead of a type Terry Reedy <tjreedy@udel.edu> - 2012-03-29 11:04 -0400
    tabs/spaces (was: Re: unittest: assertRaises() with an instance instead of a type) Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-29 09:18 +0200
      Re: tabs/spaces (was: Re: unittest: assertRaises() with an instance instead of a type) Roy Smith <roy@panix.com> - 2012-03-29 08:49 -0400
      Re: tabs/spaces Dave Angel <d@davea.name> - 2012-03-29 11:16 -0400
      Re: tabs/spaces Terry Reedy <tjreedy@udel.edu> - 2012-03-29 11:25 -0400
        Re: tabs/spaces Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-30 09:05 +0200
          Re: tabs/spaces Dave Angel <d@davea.name> - 2012-03-30 08:47 -0400
            Re: tabs/spaces Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-04-02 09:12 +0200
              Re: tabs/spaces Terry Reedy <tjreedy@udel.edu> - 2012-04-02 03:42 -0400

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