add lower-constraints

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 [1] for details.

1. http://lists.openstack.org/pipermail/openstack-dev/2018-March/128352.html

Change-Id: I0f8b1bd44cd2f401593ce079cdecce5020807051

lower-constraints.txt

@@ -0,0 +1,10 @@
+coverage===4.0
+fixtures===3.0.0
+oslotest===3.2.0
+os-testr===1.0.0
+pycrypto===2.6
+python-subunit===1.0.0
+Sphinx===1.6.5
+testrepository===0.0.18
+testscenarios===0.4
+testtools===2.2.0

test-requirements.txt

@@ -1,12 +1,10 @@
 hacking>=0.5.6
-
-coverage>=3.6
-discover
-fixtures>=0.3.14
-python-subunit
-sphinx>=1.1.2
-testrepository>=0.0.17
+coverage>=4.0
+fixtures>=3.0.0
+python-subunit>=1.0.0
+sphinx>=1.6.5
+testrepository>=0.0.18
 testscenarios>=0.4
-testtools>=0.9.32
-os-testr>=0.8.0 # Apache-2.0
-oslotest>=1.10.0 # Apache-2.0
+testtools>=2.2.0
+os-testr>=1.0.0 # Apache-2.0
+oslotest>=3.2.0 # Apache-2.0

tox.ini

@@ -32,3 +32,10 @@ show-source = true
 
 [pep8]
 ignore = E731,E226,E123
+
+[testenv:lower-constraints]
+basepython = python3
+deps =
+  -c{toxinidir}/lower-constraints.txt
+  -r{toxinidir}/test-requirements.txt
+  -r{toxinidir}/requirements.txt

zuul.d/project.yaml

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