openstack/deb-python-eventlet
Code Issues Proposed changes

greendns tests: Work around patcher/green package weirdness

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The issue can be demonstrated by running the following piece of code:

    # t.py
    from __future__ import print_function

    from eventlet.support import greendns

    import sys
    if sys.argv[1] == 'yes':
        import dns.resolver

    print(sys.argv[1], issubclass(greendns.HostsAnswer, greendns.dns.resolver.Answer))

The results:

    # Python 2.7.11
    % python t.py yes
    yes False
    % python t.py no
    no True

    # Python 3.5.1
    % python t.py yes
    yes False
    % python t.py no
    no True

Interestingly enough this particular test issue was only affecting Python
3.5+ before 861d684. Why?

* This issue appears to be caused by importing green version of a package
  being followed by importing a non-green version of the same package
* When we run tests using nose it first imports the main tests module
  (tests/__init__.py) which imports eventlet, that imports
  eventlet.convenience and that then imports eventlet.green.sockt.
* Before 861d684 on Python < 3.5 the eventlet.green.socket import mentioned
  above would fail to import greendns (because of an import cycle) so when
  running those tests greendns was only being correctly imported *after* the
  regular dns
* Since 861d684 (or on Python 3.5+) the green socket module correctly
  imports greendns which means that when the regular dns subpackages are
  being imported in this test file greendns is already imported and the
  patching issue demonstrated by the code above is in effect

The patching/greening weirdness is reported[1] now.

Fixes https://github.com/eventlet/eventlet/issues/267

This patch is contributed by Smarkets Limited.

[1] https://github.com/eventlet/eventlet/issues/316
This commit is contained in:
Jakub Stasiak
2016-05-18 14:13:09 +02:00
parent 861d684399
commit e3e6789a40
1 changed files with 1 additions and 6 deletions
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7
tests/greendns_test.py
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@@ -9,13 +9,8 @@ import time
import tests
from tests import mock
try:
import dns.rdatatype
import dns.rdtypes.IN.A
import dns.rdtypes.IN.AAAA
import dns.resolver
import dns.reversename
import dns.rrset
from eventlet.support import greendns
from eventlet.support.greendns import dns
except ImportError:
__test__ = False