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

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On 3/29/2012 3:28 AM, Ulrich Eckhardt wrote:

>> Equality comparison is by id. So this code will not do what you want.
>
>  >>> Exception('foo') == Exception('foo')
> False
>
> Yikes! That was unexpected and completely changes my idea. Any clue
> whether this is intentional? Is identity the fallback when no equality
> is defined for two objects?

Yes. The Library Reference 4.3. Comparisons (for built-in classes) puts 
is this way.
"Objects of different types, except different numeric types, never 
compare equal. Furthermore, some types (for example, function objects) 
support only a degenerate notion of comparison where any two objects of 
that type are unequal." In other words, 'a==b' is the same as 'a is b'. 
That is also the default for user-defined classes, but I am not sure 
where that is documented, if at all.

-- 
Terry Jan Reedy

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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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