[pytest-dev] Enabling viewing of rewritten AST trees as Python

[Tom Viner]

Thanks for your ideas Floris, I've managed to get it working with
your pytest_configure suggestion.

The only extra bit was having to disable reading the cached pyc files that
pytest writes, as these skip my monkeypatch.

Take a look, it's simple to use:
https://gist.github.com/tomviner/c3537c2f2b2b8172f83e

If there's any demand, I could easily make this a pip installable pytest
plugin.

On 13 November 2014 at 23:34, Floris Bruynooghe <flub at devork.be> wrote:

> Hi Tom,
>
> On 9 November 2014 19:18, Tom Viner <tom at viner.tv> wrote:
> > The four options I can think of to gain access to this variable:
> > - monkey patch rewrite.rewrite_asserts
> > - edit rewrite_asserts and paste in the logging code above:
> >     -- temporarily, by each developer, on each occasion required
> >     -- permanently, but only running when a certain debug flag is active
> > - expose the rewritten AST via a new hook
> >
> > monkey patch is my preferred option, because if I can make it work, a
> plugin
> > could be written. I just need some help to find an appropriate hook to do
> > the monkey patching before pytest gets going with the
> AssertionRewritingHook
> > and calls rewrite_asserts. Without knowledge of an early-running hook, I
> > could only get this working by patching rewrite_asserts then calling
> > pytest.main myself, see
> > https://gist.github.com/tomviner/13c95cdb1e159028fc0b
>
> Would this work by using monkeypatching, but using a method on
> _pytest.pytester.TmpTestDir which wraps around inline_run or
> inline_runsource?  That would seem like a fairly reasonable approach.
> It could simply skip with an appropriate message if the meta lib is
> importable and print the reversed python code to stdout for capsys to
> collect.
>
> If you would like to go the full plugin way I believe you just need to
> hook in before collection happens.  I imagine pytest_configure would
> be a reasonable hook for that, but have to admit I haven't tried it.
>
>
> Regards,
> Floris
>
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