Follow the new PTI for document build

For compliance with the Project Testing Interface as described in:

https://governance.openstack.org/tc/reference/project-testing-interface.html

For more detials information, please refer to:

http://lists.openstack.org/pipermail/openstack-dev/2017-December/125710.html

Change-Id: Ib02738563f5ae3712e1074a3b08c693ea7cdea79

doc/requirements.txt

+# These are needed for docs generation
+openstackdocstheme>=1.17.0 # Apache-2.0
+sphinx>=1.6.2 # BSD
+reno>=2.5.0 # Apache-2.0
+
+mock>=2.0.0 # BSD
+fixtures>=3.0.0 # Apache-2.0/BSD

tox.ini

@@ -19,7 +19,8 @@ commands = flake8
 commands = {posargs}
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+deps = -r{toxinidir}/doc/requirements.txt
+commands = sphinx-build -b html doc/source doc/build/html
 
 [testenv:cover]
 commands = python setup.py test --coverage --coverage-package-name=oslo_versionedobjects --testr-args='{posargs}'
@@ -44,4 +45,5 @@ deps = pip_missing_reqs
 commands = pip-missing-reqs -d --ignore-module=oslo_versionedobjects* --ignore-module=pkg_resources --ignore-file=oslo_versionedobjects/test.py --ignore-file=oslo_versionedobjects/tests/* oslo_versionedobjects
 
 [testenv:releasenotes]
+deps = -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html