Merge pull request #599 from Automattic/feature/travis-test-against-p…

…hp8-no-failure

Travis: add build against PHP 8.0

.travis.yml

@@ -67,8 +67,13 @@ jobs:
         # Run PHPCS against VIPCS.
         - ./bin/phpcs
 
-    # Builds which need a different distro.
+    # Builds which need a different distro or specific PHPCS version.
     - stage: test
+    - php: 8.0
+      env: PHPCS_BRANCH="dev-master"
+    - php: 8.0
+      # PHPCS 3.5.7 is the lowest version of PHPCS which supports PHP 8.0.
+      env: PHPCS_BRANCH="3.5.7"
     - php: 5.5
       dist: trusty
       env: PHPCS_BRANCH="dev-master"
@@ -98,7 +103,7 @@ before_install:
 install:
   - travis_retry composer require squizlabs/php_codesniffer:"$PHPCS_BRANCH" --no-update --no-suggest --no-scripts
   - |
-    if [[ $TRAVIS_PHP_VERSION == "nightly" ]]; then
+    if [[ $TRAVIS_PHP_VERSION == "nightly" || $TRAVIS_PHP_VERSION == "8.0" ]]; then
       # PHPUnit 7.x does not allow for installation on PHP 8, so ignore platform
       # requirements to get PHPUnit 7.x to install on nightly.
       travis_retry composer install --ignore-platform-reqs --no-suggest