Prepare test env for Django 2.0 with python 3.5

Change-Id: I657d3d5cbec9a62b4322b4f6f892ecc0b2912fa4

.zuul.yaml

@@ -26,6 +26,12 @@
     vars:
       tox_envlist: py27dj110
 
+- job:
+    name: horizon-openstack-tox-py35dj20
+    parent: horizon-openstack-tox-base
+    vars:
+      tox_envlist: py35dj20
+
 - job:
     name: horizon-selenium-headless
     parent: horizon-openstack-tox-base
@@ -39,6 +45,8 @@
         - horizon-openstack-tox-py27dj110
         - horizon-openstack-tox-py27dj19
         - horizon-openstack-tox-py27dj18
+        - horizon-openstack-tox-py35dj20:
+            voting: false
         - horizon-selenium-headless
     gate:
       jobs:

tox.ini

@@ -5,6 +5,7 @@ skipsdist = True
 
 [testenv]
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
+usedevelop = True
 setenv =
   VIRTUAL_ENV={envdir}
   INTEGRATION_TESTS=0
@@ -18,7 +19,6 @@ deps = .[test]
   -r{toxinidir}/test-requirements.txt
 commands =
   horizon: {envpython} {toxinidir}/manage.py test --settings=horizon.test.settings {posargs}
-  manage: {envpython} {toxinidir}/manage.py {posargs}
   py27: {[unit_tests]commands}
   py35: {[unit_tests]commands}
   openstack_dashboard: {envpython} {toxinidir}/manage.py test --settings=openstack_dashboard.test.settings {posargs}
@@ -51,13 +51,20 @@ commands =
   pip install -U django>=1.11,<2.0
   {[unit_tests]commands}
 
+[testenv:py35dj20]
+basepython = python3.5
+deps =
+  -r{toxinidir}/test-requirements.txt
+commands =
+  pip install -U --pre django
+  {[unit_tests]commands}
+
 [unit_tests]
 commands =
     find . -type f -name "*.pyc" -delete
     bash {toxinidir}/tools/unit_tests.sh {envpython} {toxinidir} {posargs}
 
 [testenv:pep8]
-usedevelop = True
 commands =
   {envpython} {toxinidir}/manage.py extract_messages --verbosity 0 --check-only
   flake8 {posargs}
@@ -136,6 +143,20 @@ commands =
   doc8 releasenotes/source releasenotes/notes
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
+[testenv:manage]
+# we don't need to install test-requirements.txt
+# modules in requirements.txt are installed due to usedevelop=True
+# so 'deps' can be empty.
+deps =
+commands = {envpython} {toxinidir}/manage.py {posargs}
+
+[testenv:manage-py35dj20]
+basepython = python3.5
+deps = {[testenv:manage]deps}
+commands =
+  pip install -U --pre django
+  {[testenv:manage]commands}
+
 [flake8]
 filename = *.py,django.wsgi
 exclude = .venv,.git,.tox,dist,*lib/python*,*egg,build,panel_template,dash_template,local_settings.py,*/local/*,*/test/test_plugins/*,.ropeproject,node_modules,openstack_dashboard/enabled/*