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Kristján Valur Jónsson

21 Jul 2012 21 Jul '12

9:29 p.m.

I was hit by this today. in test_hashlib.py there is this: def test_unknown_hash(self): self.assertRaises(ValueError, hashlib.new, 'spam spam spam spam spam') self.assertRaises(TypeError, hashlib.new, 1) but in hashlib.py, there is this code: except ImportError: pass # no extension module, this hash is unsupported. raise ValueError('unsupported hash type %s' % name) The code will raise ValueError when int(1) is passed in, but the unittests expect a TypeError. So, which is correct? K

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Antoine Pitrou

21 Jul 21 Jul

9:58 p.m.

On Sat, 21 Jul 2012 21:29:50 +0000 Kristján Valur Jónsson wrote:

The code will raise ValueError when int(1) is passed in, but the unittests expect a TypeError.

Well, if test_hashlib passes, surely your analysis is wrong, no? -- Software development and contracting: http://pro.pitrou.net

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Amaury Forgeot d'Arc

10:56 p.m.

2012/7/21 Antoine Pitrou :

Kristján Valur Jónsson wrote:

...
The code will raise ValueError when int(1) is passed in, but the unittests expect a TypeError.

Well, if test_hashlib passes, surely your analysis is wrong, no?

In the normal case, yes:

...
...
import hashlib hashlib.new(1) TypeError: name must be a string

But if the _hashlib extension module is not available, the python version is used and ValueError is raised:

...
...
import sys sys.modules['_hashlib'] = None import hashlib hashlib.new(1) ValueError: unsupported hash type 1

-- Amaury Forgeot d'Arc

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Guido van Rossum

22 Jul 22 Jul

12:08 a.m.

I think I see Kristján's point: the pure Python implementation handles errors differently than the C implementation, so the unittest fails if the pure Python version is enabled. I imagine this is a general problem that often occurs when a pure Python version is normally shadowed by a C extension, unless the unittest is rigged so that it tests the pure Python version as well as the C version. But it still remains a matter of judgment whether in a particular case the unittest is overspecified or the Python version is incorrect. I think that in this case Kristján's hunch is correct, and the pure Python version needs to be adjusted to pass the test. I also think this is a low priority issue since it only affects behavior of error cases. --Guido On Sat, Jul 21, 2012 at 3:56 PM, Amaury Forgeot d'Arc wrote:

2012/7/21 Antoine Pitrou :

...
Kristján Valur Jónsson wrote:

...
The code will raise ValueError when int(1) is passed in, but the unittests expect a TypeError.

Well, if test_hashlib passes, surely your analysis is wrong, no?

In the normal case, yes:

...
...
...
import hashlib hashlib.new(1) TypeError: name must be a string

But if the _hashlib extension module is not available, the python version is used and ValueError is raised:

...
...
...
import sys sys.modules['_hashlib'] = None import hashlib hashlib.new(1) ValueError: unsupported hash type 1

-- Amaury Forgeot d'Arc _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/guido%40python.org

-- --Guido van Rossum (python.org/~guido)

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Kristján Valur Jónsson

1:05 a.m.

Indeed, shame on me for not mentioning this. I rarely have the full complement of externals available when I'm doing python work, and it struck me that this unitest was failing. I suppose it should be possible to write unittests that test more than one particular implementation. K ________________________________________ Frá: python-dev-bounces+kristjan=ccpgames.com@python.org [python-dev-bounces+kristjan=ccpgames.com@python.org] fyrir hönd Amaury Forgeot d'Arc [amauryfa@gmail.com] Sent: 21. júlí 2012 22:56 To: Antoine Pitrou Cc: python-dev@python.org Efni: Re: [Python-Dev] test_hashlib 2012/7/21 Antoine Pitrou :

Kristján Valur Jónsson wrote:

...
The code will raise ValueError when int(1) is passed in, but the unittests expect a TypeError.

Well, if test_hashlib passes, surely your analysis is wrong, no?

In the normal case, yes:

...
...
import hashlib hashlib.new(1) TypeError: name must be a string

But if the _hashlib extension module is not available, the python version is used and ValueError is raised:

...
...
import sys sys.modules['_hashlib'] = None import hashlib hashlib.new(1) ValueError: unsupported hash type 1

-- Amaury Forgeot d'Arc _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/kristjan%40ccpgames.com

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R. David Murray

2:10 a.m.

On Sun, 22 Jul 2012 01:05:35 -0000, =?iso-8859-1?Q?Kristj=E1n_Valur_J=F3nsson?= wrote:

Indeed, shame on me for not mentioning this. I rarely have the full complement of externals available when I'm doing python work, and it struck me that this unitest was failing. I suppose it should be possible to write unittests that test more than one particular implementation.

It is indeed, and we have been moving the unit tests to do exactly that for the cases where there is a Python implementation as well as a C implementation. It seems like it would be appropriate to open an issue for doing that for hashlib, in addition to one for fixing this particular issue with the Python version. --David

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Gregory P. Smith

4:25 a.m.

Fixed. The TypeError in this nonsense never gonna work use case is now consistent in 2.7, 3.2 and 3.3. On Sat, Jul 21, 2012 at 7:10 PM, R. David Murray wrote:

...
Indeed, shame on me for not mentioning this. I rarely have the full complement of externals available when I'm doing

On Sun, 22 Jul 2012 01:05:35 -0000, =?iso-8859-1?Q?Kristj=E1n_Valur_J=F3nsson?= wrote: python work, and it struck me that this unitest was failing.

...
I suppose it should be possible to write unittests that test more than one particular implementation.

It is indeed, and we have been moving the unit tests to do exactly that for the cases where there is a Python implementation as well as a C implementation. It seems like it would be appropriate to open an issue for doing that for hashlib, in addition to one for fixing this particular issue with the Python version.

--David _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/greg%40krypto.org

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participants (6)

Amaury Forgeot d'Arc
Antoine Pitrou
Gregory P. Smith
Guido van Rossum
Kristján Valur Jónsson
R. David Murray