Recursive type annotations do not work in documentation tests

[lovasoa]

BPO	36810
Nosy	@gvanrossum, @ambv, @ilevkivskyi, @lovasoa
Files	test_recursive.py: Example failing file

^{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 = <Date 2019-05-19.08:50:46.687>
created_at = <Date 2019-05-06.07:34:51.772>
labels = ['interpreter-core', 'invalid', 'type-bug', '3.7']
title = 'Recursive type annotations do not work in documentation tests'
updated_at = <Date 2019-05-19.08:50:46.683>
user = 'https://github.com/lovasoa'

bugs.python.org fields:

activity = <Date 2019-05-19.08:50:46.683>
actor = 'levkivskyi'
assignee = 'none'
closed = True
closed_date = <Date 2019-05-19.08:50:46.687>
closer = 'levkivskyi'
components = ['Interpreter Core']
creation = <Date 2019-05-06.07:34:51.772>
creator = 'lovasoa'
dependencies = []
files = ['48302']
hgrepos = []
issue_num = 36810
keywords = []
message_count = 4.0
messages = ['341489', '342123', '342143', '342838']
nosy_count = 4.0
nosy_names = ['gvanrossum', 'lukasz.langa', 'levkivskyi', 'lovasoa']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue36810'
versions = ['Python 3.7']

[lovasoa]

When using documentations tests to test a function that uses typing.get_type_hints, an error is thrown.

The error is thrown when trying to get the type hints for a class that was defined in a documentation test.

I was able to reproduce it both on current and PEP-563 type annotations: https://gist.github.com/lovasoa/74ea62a89f5bf073b0e0c2f222008ae3

[ilevkivskyi]

I think this is related to doc tests being executed in a namespace where the class definition is not available. I am not sure what is the best way here, a workaround is to explicitly pass the namespace, for example this passes:

import typing
  
def f(clazz, ns):
    """
    >>> class MyClass:
    ...   my_field: 'MyClass'
    >>> f(MyClass, globals())
    """
    typing.get_type_hints(clazz, ns)

You can maybe make the ns parameter optional, but it still doesn't look like a good solution.

[gvanrossum]

I don't think there's an actionable bug here.

[ilevkivskyi]

I don't think there's an actionable bug here.

OK, then taking into account there is a decent workaround, I am closing this.