Parallelize CI workflow by adding Django versions to job matrix (#1219)

* add `django-version` to job matrix

* adjust job name

* add django 2.2 and adjust exclude matrix

* remove max-parallel restriction

* change comments to be clearer

* remove extra newline

* remove whitespace

* chore: add success test

decouple successful from specific matrix builds
to avoid GH admin intervention as we update
our supported matrix.

---------

Co-authored-by: Darrel O'Pry <darrel.opry@spry-group.com>

.github/workflows/test.yml

@@ -4,12 +4,27 @@ on: [push, pull_request]
 
 jobs:
   build:
+    name: build (Python ${{ matrix.python-version }}, Django ${{ matrix.django-version }})
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
-      max-parallel: 5
       matrix:
         python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
+        django-version: ['2.2', '3.2', '4.0', '4.1', 'main']
+        exclude:
+          # https://docs.djangoproject.com/en/dev/faq/install/#what-python-version-can-i-use-with-django
+
+          # Python 3.10+ is not supported by Django 2.2
+          - python-version: '3.10'
+            django-version: '2.2'
+
+          # Python 3.7 is not supported by Django 4.0+
+          - python-version: '3.7'
+            django-version: '4.0'
+          - python-version: '3.7'
+            django-version: '4.1'
+          - python-version: '3.7'
+            django-version: 'main'
 
     steps:
     - uses: actions/checkout@v2
@@ -42,8 +57,18 @@ jobs:
     - name: Tox tests
       run: |
         tox -v
+      env:
+        DJANGO: ${{ matrix.django-version }}
 
     - name: Upload coverage
       uses: codecov/codecov-action@v1
       with:
         name: Python ${{ matrix.python-version }}
+
+  success:
+    needs: build
+    runs-on: ubuntu-latest
+    name: Test successful
+    steps:
+      - name: Success
+        run: echo Test successful

tox.ini

@@ -19,6 +19,14 @@ python =
     3.10: py310
     3.11: py311
 
+[gh-actions:env]
+DJANGO =
+    2.2: dj22
+    3.2: dj32
+    4.0: dj40
+    4.1: dj41
+    main: djmain
+
 [pytest]
 django_find_project = false
 addopts =