Travis CI improvements (#37840)

.travis.yml

@@ -1,4 +1,3 @@
-sudo: false
 dist: bionic
 addons:
   apt:
@@ -14,7 +13,17 @@ addons:
     sources:
       - sourceline: ppa:savoury1/ffmpeg4
 
-matrix:
+python:
+  - "3.7.1"
+  - "3.8"
+
+env:
+  - TOX_ARGS="-- --test-group-count 4 --test-group 1"
+  - TOX_ARGS="-- --test-group-count 4 --test-group 2"
+  - TOX_ARGS="-- --test-group-count 4 --test-group 3"
+  - TOX_ARGS="-- --test-group-count 4 --test-group 4"
+
+jobs:
   fast_finish: true
   include:
     - python: "3.7.1"
@@ -23,13 +32,11 @@ matrix:
       env: TOXENV=pylint PYLINT_ARGS=--jobs=0 TRAVIS_WAIT=30
     - python: "3.7.1"
       env: TOXENV=typing
-    - python: "3.7.1"
-      env: TOXENV=py37
 
 cache:
   pip: true
   directories:
     - $HOME/.cache/pre-commit
-install: pip install -U tox
+install: pip install -U tox tox-travis
 language: python
-script: ${TRAVIS_WAIT:+travis_wait $TRAVIS_WAIT} tox --develop
+script: ${TRAVIS_WAIT:+travis_wait $TRAVIS_WAIT} tox --develop ${TOX_ARGS-}