Break cycle dependency with os-api-ref

openstackdocstheme requires os-api-ref for testing, but os-api-ref requires
openstackdocstheme. To break this, make os-api-ref an optional test
requirement.

Change-Id: Ibbd01f63a516a49133cd8cdd4cf0cfe69bbaecaf

setup.cfg

@@ -19,6 +19,12 @@ classifier =
     Programming Language :: Python :: 3.5
     Topic :: Documentation
 
+[extras]
+test =
+    # os-api-ref needs openstackdocstheme which needs os-api-ref (cycle dep)
+    # so put os-api-ref in extras to make it an optional test dependency
+    os-api-ref>=1.0.0 # Apache-2.0
+
 [global]
 setup-hooks =
     pbr.hooks.setup_hook

test-requirements.txt

@@ -8,5 +8,3 @@ hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 sphinx>=1.6.2 # BSD
 
 reno!=2.3.1,>=1.8.0 # Apache-2.0
-
-os-api-ref>=1.0.0 # Apache-2.0

tox.ini

@@ -6,6 +6,7 @@ envlist = pep8
 usedevelop = False
 install_command = {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 deps = -r{toxinidir}/test-requirements.txt
+    .[test]
 setenv = VIRTUAL_ENV={envdir}
          BRANCH_NAME=master
          CLIENT_NAME=openstackdocstheme