memcache tests are skipped on python 3

[Clint Byrum]

Currently the py34 test environment loads a set of test requirements that don't include python-memcached. This leads to tests being skipped, and an incompatibility for python-keystoneclient on python3.

Ran 1073 tests in 10.056s
PASSED (id=0, skips=3)

keystoneclient/tests/unit/test_auth_token_middleware.py: @testtools.skipUnless(memcached_available(), 'memcached not available')
keystoneclient/tests/unit/test_auth_token_middleware.py: @testtools.skipUnless(memcached_available(), 'memcached not available')
keystoneclient/tests/unit/test_auth_token_middleware.py: @testtools.skipUnless(memcached_available(), 'memcached not available')

[Victor Stinner (vstinner)]

> memcache tests are skipped on python 3

Tests are skipped for a good reason: python-memcached 1.54 (latest release) doesn't work on Python 3.

Hum, on a fresh system, memcache tests are also skipped on Python 2 because python-memcached is missing in test dependencies! I wrote a first patch to enable these tests on Python 2:
https://review.openstack.org/#/c/176778/

I also wrote a patch to finish the python-memcached port to Python 3:
https://github.com/linsomniac/python-memcached/pull/67

When python-memcached will really work on Python 3, I will write a second patch to enable memcache tests of keystoneclient on Python 3 too.

[Victor Stinner (vstinner)]

Brant Knudson wrote that the middleware in python-keystoneclient was deprecated in Juno. We may remove it during the Liberty cycle. The code was moved to a new keystonemiddle component.

The bug is still valid for keystonemiddle.

[Morgan Fainberg (mdrnstm)]

This will not be fixed in python-keystoneclient as python-keystoneclient will be dropping the middleware in the Liberty cycle.

[Morgan Fainberg (mdrnstm)]

python-keystonemiddleware is not the correct LP project.

[Morgan Fainberg (mdrnstm)]

This is being marked as medium priority for the keystonemiddleware package, as the issue is that the python-memcache library is not fully python3 compatible (and downright poorly built). keystonemiddleware should move to dogpile.cache instead and allow for various generic caching backends that can work with python2 and 3 as deployers need.

[Steve Martinelli (stevemar)]

i believe this was fixed in patch:

https://github.com/openstack/keystonemiddleware/commit/c07ee616ae1d7e1a212dd17ba1f16a177c7acf3d

also python-memcached 1.56 and newer supports py3

we can see that 312 tests are ran for py27 and for p37

tests for py27: http://logs.openstack.org/40/205440/10/check/gate-keystonemiddleware-python27/df85167/testr_results.html.gz
tests for py34: http://logs.openstack.org/40/205440/10/check/gate-keystonemiddleware-python34/c713cb1/testr_results.html.gz