add lower-constraints job

Create a tox environment for running the unit tests against the lower
bounds of the dependencies.

Create a lower-constraints.txt to be used to enforce the lower bounds
in those tests.

Add openstack-tox-lower-constraints job to the zuul configuration.

See http://lists.openstack.org/pipermail/openstack-dev/2018-March/128352.html
for more details.

Change-Id: I5a5a297c8b16a507a7d2dd65f2d11363d1d238d2
Depends-On: https://review.openstack.org/555034
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

lower-constraints.txt

@@ -0,0 +1,51 @@
+alabaster==0.7.10
+appdirs==1.4.3
+Babel==2.5.3
+certifi==2018.1.18
+chardet==3.0.4
+click==6.7
+coverage==4.5.1
+docutils==0.14
+dulwich==0.19.0
+extras==1.0.0
+fixtures==3.0.0
+flake8==2.5.5
+Flask==0.12.2
+hacking==0.12.0
+idna==2.6
+imagesize==1.0.0
+iso8601==0.1.12
+itsdangerous==0.24
+Jinja2==2.10
+keystoneauth1==3.4.0
+libvirt-python==4.0.0
+linecache2==1.0.0
+MarkupSafe==1.0
+mccabe==0.2.1
+mock==2.0.0
+mox3==0.25.0
+openstackdocstheme==1.20.0
+os-client-config==1.29.0
+oslotest==3.3.0
+pbr==3.1.1
+pep8==1.5.7
+pyflakes==0.8.1
+Pygments==2.2.0
+python-mimeparse==1.6.0
+python-subunit==1.2.0
+pytz==2018.3
+PyYAML==3.12
+requests==2.18.4
+requestsexceptions==1.4.0
+six==1.11.0
+snowballstemmer==1.2.1
+Sphinx==1.6.5
+sphinxcontrib-websupport==1.0.1
+stevedore==1.28.0
+testrepository==0.0.20
+testscenarios==0.5.0
+testtools==2.3.0
+traceback2==1.4.0
+unittest2==1.1.0
+urllib3==1.22
+Werkzeug==0.14.1

tox.ini

@@ -34,3 +34,10 @@ show-source = True
 ignore = E123,E125
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build
+
+[testenv:lower-constraints]
+basepython = python3
+deps =
+  -c{toxinidir}/lower-constraints.txt
+  -r{toxinidir}/test-requirements.txt
+  -r{toxinidir}/requirements.txt

zuul.d/project.yaml

@@ -3,7 +3,9 @@
       jobs:
         - sushy-tools-tempest-dsvm-ironic-ipa-partition-redfish-src
         - build-openstack-sphinx-docs
+        - openstack-tox-lower-constraints
     gate:
       jobs:
         - sushy-tools-tempest-dsvm-ironic-ipa-partition-redfish-src
         - build-openstack-sphinx-docs
+        - openstack-tox-lower-constraints