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: I84da413225e9410be890abf32a22e4409100d7fa

doc/requirements.txt

@@ -0,0 +1,7 @@
+# The order of packages is significant, because pip processes them in the order
+# of appearance. Changing the order has an impact on the overall integration
+# process, which may cause wedges in the gate later.
+# These are needed for docs generation
+openstackdocstheme>=1.18.1 # Apache-2.0
+sphinx!=1.6.6,>=1.6.2 # BSD
+reno>=2.5.0 # Apache-2.0

test-requirements.txt

@@ -6,14 +6,9 @@ ipaddress>=1.0.16;python_version<'3.3' # PSF
 mock>=2.0.0 # BSD
 netaddr>=0.7.18 # BSD
 
-# this is required for the docs build jobs
-sphinx!=1.6.6,>=1.6.2 # BSD
-openstackdocstheme>=1.18.1 # Apache-2.0
-
 oslotest>=3.2.0 # Apache-2.0
 oslo.i18n>=3.15.3 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
-reno>=2.5.0 # Apache-2.0
 
 # Bandit security code scanner
 bandit>=1.1.0 # Apache-2.0

tox.ini

@@ -22,7 +22,8 @@ commands =
 commands = {posargs}
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+deps = -r{toxinidir}/doc/requirements.txt
+commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:cover]
 commands = python setup.py test --coverage --coverage-package-name=oslo_serialization --testr-args='{posargs}'
@@ -43,4 +44,5 @@ deps = pip_missing_reqs
 commands = pip-missing-reqs -d --ignore-module=oslo_serialization* --ignore-module=pkg_resources --ignore-file=oslo_serialization/test.py --ignore-file=oslo_serialization/tests/* oslo_serialization
 
 [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