[Python-ideas] doctest

Devin Jeanpierre jeanpierreda at gmail.com
Fri Mar 2 03:49:59 CET 2012

On Thu, Mar 1, 2012 at 9:31 PM, Mark Janssen <dreamingforward at gmail.com> wrote:
> I just thought of something:  isn't the obvious solution is for doctest to
> test the type of an expression's output and if it's in the set of unordered
> types {set, dict} to run sort() on it?  Then the docstring author can just
> put the (sorted) output of what's expected....

It's the solution people seem to think of first, so it's definitely
fairly obvious. It's not a big improvement, though. The original
problem is that dict order shouldn't matter, but in doctest it does,
making dicts unusable in the normal doctest style. Making it a
specific dict order be the prominent one lets you use dicts in
doctest, but you have to sort the dicts and rewrite the doctest to
take that into account. And even so, some dicts cannot be represented
this way. For example, the dict {1:2, "hello": world} cannot be sorted
in Python 3, so it won't work in this scheme.

The solution I used was to ast.literal_eval on both sides every time
you compare output. This way you don't have to care about dict order,
or whitespace, or any of these things for Python objects. (There is a
flag for not caring about whitespace, but this would inappropriately
collapse e.g. the whitespace inside string literals inside a dict. So
imo this kills two birds with one stone).

-- Devin

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