Convert logging usage doctests to testable snippets

[tseaver]

Toward #212 / #2535.

[dhermes]

@jonparrott Can you also peek at these?

[theacodes]

This looks okay to me as a start, but it is concerning to see so much setup/cleanup logic in the snippet function body. Pytest fixtures can help a lot with that, or just having separate test functions for each snippet. We do both in python-docs-samples.

[daspecster]

Fixture example from python-docs-samples.

@pytest.fixturedefexample_log():
client=logging.Client()
logger=client.logger(TEST_LOGGER_NAME)
text='Hello, world.'logger.log_text(text)
returntext

This looks pretty nice!
http://doc.pytest.org/en/latest/fixture.html

[dhermes]

@tseaver Here is a proof of concept for running readable interpreter snippets without worrying about calling eval / exec etc.

First, create a fake module (or any object really) with our content in the __doc__

>>>importtypes>>>fake_mod=types.ModuleType('haha-nope')
>>>fake_mod.__doc__="""\... Here is some prose, and then a dragon appears... and it makes sure division::...... >>> a = 45... >>> a / 3... 15...... and then the bunny hops down the lane and we... find out we have to print a null::...... >>> b = {}... >>> v = b.get('anything')... >>> v... >>> print(v)... None... """

then hand that object off to doctest.run_docstring_examples

>>>importdoctest>>>fake_globals= {}
>>>doctest.run_docstring_examples(fake_mod, fake_globals, verbose=False, name='foo')
>>>doctest.run_docstring_examples(fake_mod, fake_globals, verbose=True, name='foo')
FindingtestsinfooTrying:
a=45ExpectingnothingokTrying:
a/3Expecting:
15okTrying:
b= {}
ExpectingnothingokTrying:
v=b.get('anything')
ExpectingnothingokTrying:
vExpectingnothingokTrying:
print(v)
Expecting:
Noneok