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.

Add missing dev packages for libxml and libxslt to the bindep config
file.

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

Change-Id: I4a51633916661bdfa926eb231b8e482628887e90
Depends-On: https://review.openstack.org/555034
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

.zuul.yaml

@@ -0,0 +1,7 @@
+- project:
+    check:
+      jobs:
+        - openstack-tox-lower-constraints
+    gate:
+      jobs:
+        - openstack-tox-lower-constraints

bindep.txt

@@ -7,3 +7,7 @@ python-dev [platform:dpkg]
 python3-all [platform:dpkg !platform:ubuntu-precise]
 python3-all-dev [platform:dpkg !platform:ubuntu-precise]
 python3-devel [platform:fedora]
+libxml2-dev [platform:dpkg]
+libxslt1-dev [platform:dpkg]
+libxml2-devel [platform:rpm]
+libxslt-devel [platform:rpm]

lower-constraints.txt

@@ -0,0 +1,46 @@
+alabaster==0.7.10
+astroid==1.6.2
+Babel==2.3.4
+bashate==0.5.1
+chardet==3.0.4
+demjson==2.2.2
+doc8==0.6.0
+docutils==0.11
+dulwich==0.15.0
+extras==1.0.0
+fixtures==3.0.0
+flake8==2.5.5
+hacking==0.12.0
+imagesize==0.7.1
+iso8601==0.1.11
+isort==4.3.4
+Jinja2==2.10
+lazy-object-proxy==1.3.1
+linecache2==1.0.0
+lxml==3.4.1
+MarkupSafe==1.0
+mccabe==0.2.1
+mock==2.0.0
+openstackdocstheme==1.18.1
+pbr==2.0.0
+pep8==1.5.7
+pyflakes==0.8.1
+Pygments==2.2.0
+pylint==1.7.1
+python-mimeparse==1.6.0
+python-subunit==1.0.0
+pytz==2013.6
+PyYAML==3.12
+reno==2.5.0
+requests==2.14.2
+restructuredtext-lint==1.1.1
+six==1.10.0
+snowballstemmer==1.2.1
+Sphinx==1.6.5
+sphinxcontrib-websupport==1.0.1
+stevedore==1.20.0
+testrepository==0.0.18
+testtools==2.2.0
+traceback2==1.4.0
+unittest2==1.1.0
+wrapt==1.7.0

tox.ini

@@ -55,3 +55,13 @@ exclude=.venv,.git,.tox,dist,*lib/python*,*egg,build,doc/source/conf.py
 # 28 is currently the most complex thing we have
 max-complexity=29
 ignore = H101
+
+[testenv:lower-constraints]
+basepython = python3
+# Install also sitemap scraping tool, not installed by default
+# therefore not in requirements file
+deps =
+  scrapy>=1.0.0
+  -c{toxinidir}/lower-constraints.txt
+  -r{toxinidir}/test-requirements.txt
+  -r{toxinidir}/requirements.txt