[TIP] Functions for tests instead of classes

Michael Foord fuzzyman at voidspace.org.uk
Thu Mar 4 14:33:01 PST 2010

On 04/03/2010 22:03, Ryan Freckleton wrote:
> On Wed, Mar 3, 2010 at 12:15 PM, Michael Foord 
> <fuzzyman at voidspace.org.uk <mailto:fuzzyman at voidspace.org.uk>> wrote:
> <snip>
>     Once Holger and Benjamin have worked on their ast transformation
>     code it should be possible to add this to simpletest for better
>     failure messages with plain asserts.
> <snip>
> Does that mean we're going to get pretty asserts through ast 
> transforms? As in:

Well, not in unittest itself but in some extension of unittest...

There is an implementation that could be adapted fairly easily:


This uses the ast module which is new in Python 2.6, but it could be 
backported to use _ast for Python 2.5. There is also an old version 
called "_assertionold.py" that uses the compiler module present in 
Python 2.4.

There is also code in nose that does something similar (stack 
introspection rather than ast transformation I *believe*) in nose. If 
unittest had a good extension API this could just be implemented as a 
unittest extension...

All the best,


>     assert obj.froddle() == "baz"
> gets transformed into like (or at least functionally equivalent to):
> result = object.froddle()
> expected = "baz"
> assert result == expected, "%s != %s" % (result, expected)
> If so, that's fantastic! The same thought crossed my mind to implement 
> that with ast transforms, but I don't have enough ast-fu to implement it.
> =====
> --Ryan E. Freckleton


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