doctest doesn't find nested functions

[danb37]

BPO	1650090
Nosy	@tim-one, @bitdancer, @jayvdb
Files	doctest_nested_functions.diff: patch against trunk revision 54419 doctest_nested_functions-py3.6.diff: Ziga's patch amended version for Python 3.6 doctest_nested_functions-py3.6.diff: Python 3.6-remove unnecessary if clause

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2007-02-01.19:20:32.000>
labels = ['type-bug', 'tests']
title = "doctest doesn't find nested functions"
updated_at = <Date 2015-11-08.07:58:46.085>
user = 'https://bugs.python.org/danb37'

bugs.python.org fields:

activity = <Date 2015-11-08.07:58:46.085>
actor = 'jayvdb'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Tests']
creation = <Date 2007-02-01.19:20:32.000>
creator = 'danb37'
dependencies = []
files = ['7750', '40977', '40978']
hgrepos = []
issue_num = 1650090
keywords = ['patch']
message_count = 4.0
messages = ['51831', '51832', '51833', '110519']
nosy_count = 6.0
nosy_names = ['tim.peters', 'zseil', 'pjdelport', 'danb37', 'r.david.murray', 'jayvdb']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue1650090'
versions = ['Python 2.7', 'Python 3.4', 'Python 3.5', 'Python 3.6']

[danb37]

If a nested function has doctests, they won't be run:
{{{
def f():
  '''
  >>> 'a'
  'a'
  '''

  def g():
    '''
    >>> 'a'
    'b'
    '''
    pass

pass
}}}

DocTestFinder will only find f's doctest and won't recurse to find g's, surprising the programmer when they (hopefully) discover that their inner doctest is incorrect!

[pjdelport]

DocTestFinder uses object inspection to find docstrings, which doesn't really allow this kind of thing: g isn't created until f is actually run.

Making this possible would probably require implementing an alternate doctest finder based on source code inspection (via the new _ast module?).

[zseil]

Here is a patch that implements this new functionality.
I don't know how desireable this feature is, I just
wanted to see if it could be done.
File Added: doctest_nested_functions.diff

[BreamoreBoy]

I believe that there could be interest in this, has anyone taken over doctest from tim_one?