Another travis update

Author: Yang

.travis.yml

@@ -1,36 +1,45 @@
 language: php
 sudo: false
 cache:
-    directories:
-        - $HOME/.composer/cache/files
-        - $HOME/symfony-bridge/.phpunit
+  directories:
+    - $HOME/.composer/cache/files
+    - $HOME/symfony-bridge/.phpunit
 env:
-    global:
-        - PHPUNIT_FLAGS="-v"
-        - SYMFONY_PHPUNIT_DIR="$HOME/symfony-bridge/.phpunit"
+  global:
+    - PHPUNIT_FLAGS="-v"
+    - SYMFONY_PHPUNIT_DIR="$HOME/symfony-bridge/.phpunit"
 matrix:
-    fast_finish: true
-    include:
-          # Minimum supported dependencies with the latest and oldest PHP version
-        - php: 7.4
-          env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" SYMFONY_DEPRECATIONS_HELPER="weak_vendors"
-        - php: 7.3
-          env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" SYMFONY_DEPRECATIONS_HELPER="weak_vendors"
-          # Test the latest stable release
-        - php: 7.3
-        - php: 7.4
-          env: COVERAGE=true PHPUNIT_FLAGS="-v --coverage-text"
-          # Test LTS versions. This makes sure we do not use Symfony packages with version greater
-          # than 2 or 3 respectively. Read more at https://github.com/symfony/lts
-        - php: 7.4
-          env: DEPENDENCIES="symfony/lts:^2"
-        - php: 7.4
-          env: DEPENDENCIES="symfony/lts:^3"
-          # Latest commit to master
-        - php: 7.4
-
+  fast_finish: true
+  include:
+    # Minimum supported dependencies with the latest and oldest PHP version
+    - php: 7.4
+      env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" SYMFONY_DEPRECATIONS_HELPER="weak_vendors"
+    - php: 7.2
+      env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" SYMFONY_DEPRECATIONS_HELPER="weak_vendors"
+      # Test the latest stable release
+    - php: 7.2
+    - php: 7.3
+    - php: 7.4
+      env: COVERAGE=true PHPUNIT_FLAGS="-v --coverage-text"
+      # Test LTS versions. This makes sure we do not use Symfony packages with version greater
+      # than 2 or 3 respectively. Read more at https://github.com/symfony/lts
+      # Latest commit to master
+    - php: 7.4
+      env: STABILITY="dev"
+  allow_failures:
+    # Dev-master is allowed to fail.
+    - env: STABILITY="dev"
+before_install:
+  - if [[ $COVERAGE != true ]]; then phpenv config-rm xdebug.ini || true; fi
+  - if ! [ -z "$STABILITY" ]; then composer config minimum-stability ${STABILITY}; fi;
+  - if ! [ -v "$DEPENDENCIES" ]; then composer require --no-update ${DEPENDENCIES}; fi;
 install:
-  - composer update ${COMPOSER_FLAGS} --no-progress --no-suggest --ansi
-
+  # To be removed when this issue will be resolved: https://github.com/composer/composer/issues/5355
+  - if [[ "$COMPOSER_FLAGS" == *"--prefer-lowest"* ]]; then composer update --prefer-dist --no-interaction --prefer-stable --quiet; fi
+  - composer update ${COMPOSER_FLAGS} --prefer-dist --no-interaction
+  - ./vendor/bin/simple-phpunit install
 script:
-  - vendor/bin/simple-phpunit
+  - composer validate --strict --no-check-lock
+  # simple-phpunit is the PHPUnit wrapper provided by the PHPUnit Bridge component and
+  # it helps with testing legacy code and deprecations (composer require symfony/phpunit-bridge)
+  - ./vendor/bin/simple-phpunit $PHPUNIT_FLAGS