Preparation for Django 3.0 and 3.1 support (1)

This commit enables non-voting unit test jobs with Django 3.0/3.1.

PendingDeprecationWarning is added to PYTHONWARNINGS in tox.ini.
PendingDeprecationWarning in Django 3.0+ includes deprecation warnings
on what will be dropped in Django 4.0 and they cannot be addressed
as long as we use Django 2.2.

Change-Id: I44e511ddc1d93fc3e2b68393b88c5f2cd1360854

.zuul.d/django-jobs.yaml

@@ -17,15 +17,21 @@
     pre-run: playbooks/horizon-tox-django/pre.yaml
     run: playbooks/horizon-tox-django/run.yaml
     vars:
-      tox_envlist: py36
+      tox_envlist: py38
     required-projects:
       - name: openstack/horizon
 
 - job:
-    name: horizon-tox-python3-django22
+    name: horizon-tox-python3-django30
     parent: horizon-tox-python3-django
     vars:
-      django_version: '>=2.2,<3.0'
+      django_version: '>=3.0,<3.1'
+
+- job:
+    name: horizon-tox-python3-django31
+    parent: horizon-tox-python3-django
+    vars:
+      django_version: '>=3.1,<3.2'
 
 - project-template:
     name: horizon-non-primary-django-jobs
@@ -37,10 +43,15 @@
         # to run tests with different versions of Django.
         # We specify a job in openstack-python3-wallaby-jobs(-horizon)
         # to keep this project template as it is used in horizon plugins.
-        - openstack-tox-py38
         # NOTE: We keep it as a template even though it is not used now.
-        # - horizon-tox-python3-django22
+        - openstack-tox-py38
+        - horizon-tox-python3-django30:
+            voting: false
+        - horizon-tox-python3-django31:
+            voting: false
     gate:
       jobs:
         - openstack-tox-py38
-        # - horizon-tox-python3-django22
+        # Skip these until the django3.x jobs become voting.
+        # - horizon-tox-python3-django30
+        # - horizon-tox-python3-django31

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 3.1
-envlist = pep8,py36,py38,releasenotes,npm
+envlist = pep8,py36,py38,releasenotes,npm,py3-dj{30,31}
 skipsdist = True
 # Automatic envs (pyXX) will only use the python version appropriate to that
 # env and ignore basepython inherited from [testenv] if we set
@@ -13,8 +13,8 @@ usedevelop = True
 setenv =
   VIRTUAL_ENV = {envdir}
   PYTHONDONTWRITEBYTECODE = 1
-  PYTHONWARNINGS = once
-  py{3,36,37}:PYTHONWARNINGS = once,ignore::ImportWarning:backports
+  PYTHONWARNINGS = once,ignore::PendingDeprecationWarning
+  py{3,36,37}:PYTHONWARNINGS = once,ignore::PendingDeprecationWarning,ignore::ImportWarning:backports
 
 whitelist_externals =
   bash
@@ -24,6 +24,8 @@ deps =
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 commands =
+  dj30: pip install django>=3.0,<3.1
+  dj31: pip install django>=3.1,<3.2
   find . -type f -name "*.pyc" -delete
   bash {toxinidir}/tools/unit_tests.sh {toxinidir} {posargs}