Added testing against Django 2.2a1. (#6422)

* Added testing against Django 2.2a1.
* Allow failures for Django 2.2

Author: auvipy

.travis.yml

@@ -12,15 +12,18 @@ matrix:
       - { python: "3.5", env: DJANGO=1.11 }
       - { python: "3.5", env: DJANGO=2.0 }
       - { python: "3.5", env: DJANGO=2.1 }
+      - { python: "3.5", env: DJANGO=2.2 }
       - { python: "3.5", env: DJANGO=master }
 
       - { python: "3.6", env: DJANGO=1.11 }
       - { python: "3.6", env: DJANGO=2.0 }
       - { python: "3.6", env: DJANGO=2.1 }
+      - { python: "3.6", env: DJANGO=2.2 }
       - { python: "3.6", env: DJANGO=master }
 
       - { python: "3.7", env: DJANGO=2.0 }
       - { python: "3.7", env: DJANGO=2.1 }
+      - { python: "3.7", env: DJANGO=2.2 }
       - { python: "3.7", env: DJANGO=master }
 
       - { python: "3.7", env: TOXENV=base }
@@ -37,6 +40,7 @@ matrix:
 
     allow_failures:
       - env: DJANGO=master
+      - env: DJANGO=2.2
 
 install:
     - pip install tox tox-venv tox-travis

tox.ini

@@ -3,6 +3,7 @@ envlist =
        {py27,py34,py35,py36}-django111,
        {py34,py35,py36,py37}-django20,
        {py35,py36,py37}-django21
+       {py35,py36,py37}-django22
        {py35,py36,py37}-djangomaster,
        base,dist,lint,docs,
 
@@ -11,6 +12,7 @@ DJANGO =
     1.11: django111
     2.0: django20
     2.1: django21
+    2.2: django22
     master: djangomaster
 
 [testenv]
@@ -23,6 +25,7 @@ deps =
         django111: Django>=1.11,<2.0
         django20: Django>=2.0,<2.1
         django21: Django>=2.1,<2.2
+        django22: Django>=2.2a1,<3.0
         djangomaster: https://github.com/django/django/archive/master.tar.gz
         -rrequirements/requirements-testing.txt
         -rrequirements/requirements-optionals.txt