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While working to improve pypy's compliance with cpython2.7
I added more tests to the ast module test suite.
They may be of interest here too...

Please upload to Rietveld. I have a few comments to make.

Hi Benjamin, we know have rietveld directly integrated in the tracker, so it might be time to add you comments? If you still can remember them, given it passed some time :)

OK I'll look at it and respin with the comments in mind

Here we are, I left the exact messages for raised exceptions as comments so they can easily be checked in case of test failure...
Does that look OK ?

You still haven't explained why including multiline literals is a good idea.
Also, the reason we avoid matching exact messages is it can vary across implementations. You can still do an accurate test with something like self.assertIn("foobar", str(e))

I was testing exact matches on the strings because I think pypy wants to be as compliant as possible with cpython, and IMHO that include exception msgs as far as possible. I don't see any reason to be different just for the sake of it.
As a user I'd find strange not to get same exc msgs from different implementations, and it'll make me loose some time digging why those difference exist...
Back to the patch:
The multiline (and also differing offsets) are there for testing .lineno & .col_offset AST node's attributes. (there was a bug in pypy's implementation of those back then...)
Do you want that explained in the comment ?
Do you want me to add "self.assertIn("foobar", str(e))" in the tests, remove the comments or let them as in the patch #2 ?

> I think pypy wants to be as compliant as possible with cpython, and
> IMHO that include exception msgs as far as possible. I don't see any
> reason to be different just for the sake of it.
>
> As a user I'd find strange not to get same exc msgs from different
> implementations, and it'll make me loose some time digging why those
> difference exist...
The language reference purposefully makes no guarantee about the error messages, and in some cases about exception types too (AttributeError vs. TypeError), so your feeling contradict Python’s rules.

2011年6月27日 Vincent Legoll <report@bugs.python.org>:
>
> Vincent Legoll <vincent.legoll@gmail.com> added the comment:
>
> I was testing exact matches on the strings because I think pypy wants to be as compliant as possible with cpython, and IMHO that include exception msgs as far as possible. I don't see any reason to be different just for the sake of it.
It's not difference just for the sake of it. Exact compatibility with
errors messages is not particularly useful as long as they have the
same semantic meaning.
>
> As a user I'd find strange not to get same exc msgs from different implementations, and it'll make me loose some time digging why those difference exist...
The usually mean the same thing; they're just worded differently.
>
> Back to the patch:
>
> The multiline (and also differing offsets) are there for testing .lineno & .col_offset AST node's attributes. (there was a bug in pypy's implementation of those back then...)
>
> Do you want that explained in the comment ?
>
> Do you want me to add "self.assertIn("foobar", str(e))" in the tests, remove the comments or let them as in the patch #2 ?
If you want, you can test the exc message with the assertIn pattern.
I don't find there's much potential for mistaking where the attribute
error is in "x.not_an_attribute". :)

* removed the comments for exc msgs
* added explanation to multiline statements
* added 2 tests to test_AST_objects()
Regarding Éric's comment, I'm starting to wonder if those Exception tests should be added to cpython's testsuite. Maybe that would only be beneficial for pypy...

New changeset 3143cadb2f2d by Benjamin Peterson in branch '2.7':
add more ast tests (closes #11302)
http://hg.python.org/cpython/rev/3143cadb2f2d
New changeset e8d47cbe9b6f by Benjamin Peterson in branch '3.2':
add more ast tests (closes #11302)
http://hg.python.org/cpython/rev/e8d47cbe9b6f
New changeset 323cf9acbccd by Benjamin Peterson in branch 'default':
merge 3.2 (#11302)
http://hg.python.org/cpython/rev/323cf9acbccd