feature #1111 Travis configuration updates and comments (michaelKaefer)

This PR was squashed before being merged into the master branch.

Discussion
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Travis configuration updates and comments

This PR contains 3 independent commits.

Commits
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78e321f Travis configuration updates and comments

Author: javiereguiluz

.travis.yml

@@ -1,18 +1,36 @@
+# Ensure that PHP is installed in Travis' build environment. Travis provides several versions of
+# PHP like 5.6, 7.0, 7.1, 7.2, 7.3, 7.4, etc., each of them including XDebug and PHPUnit.
 language: php
 
+# Travis can cache content between builds. This speeds up the build process and saves resources.
 cache:
   yarn: true
   directories:
+    # Cache composer packages so "composer install" is faster.
     - $HOME/.composer/cache/files
+    # Cache the directory where Symfony stores its slightly modified version of PHPUnit.
     - ./bin/.phpunit
+    # Cache the Symfony binary's directory so that it does not have to be reinstalled.
+    - $HOME/.symfony
 
 env:
   global:
+    # Symfony's PHPUnit bridge provides a modified version of PHPUnit. The modified PHPUnit is
+    # written to a directory that can be configured by the SYMFONY_PHPUNIT_DIR env var, or in
+    # the same directory as the simple-phpunit if it is not provided. It's also possible to set
+    # this env var in the phpunit.xml.dist file.
     - SYMFONY_PHPUNIT_DIR=./bin/.phpunit
     - SYMFONY_DEPRECATIONS_HELPER=9
     - ACTION="install"
+    # Add the Symfony binary's path to PATH.
+    - PATH="$HOME/.symfony/bin:$PATH"
 
+# Defines all jobs which Travis will run in parallel. For each PHP version we support we will run one job.
 matrix:
+  # With fast finishing enabled, Travis CI will mark your build as finished as soon as one of two
+  # conditions are met: The only remaining jobs are allowed to fail, or a job has already failed. In
+  # these cases, the status of the build can already be determined, so there’s no need to wait around
+  # until the other jobs finish.
   fast_finish: true
   include:
     - php: 7.2
@@ -23,39 +41,39 @@ matrix:
 
 before_install:
   - '[[ "$TRAVIS_PHP_VERSION" == "7.4snapshot" ]] || phpenv config-rm xdebug.ini'
-  - composer self-update
-  # Set memory to max (memory fail)
+  # Set memory to max (memory fail).
   - '[[ "$ACTION" == "install" ]] || echo "memory_limit=-1" >> ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini'
-  # Set stability to dev to allow 4.4dev and 5.0dev
+  # Set stability to dev to allow 4.4dev and 5.0dev.
   - '[[ "$ACTION" == "install" ]] || composer config minimum-stability dev'
-  # Change version of symfony when need
+  # Change version of symfony when need.
   - '[[ "$ACTION" == "install" ]] || composer config extra.symfony.require $SYMFONY'
+  # If it is available update the Symfony binary, if not install it.
+  - if symfony self:version; then symfony self:update ; else wget https://get.symfony.com/cli/installer -O - | bash ; fi
 
 install:
   - php -r "echo ini_get('memory_limit').PHP_EOL;"
-  # install or update
+  # Install or update Composer packages including dev dependencies listed in require-dev.
   - composer $ACTION
   - ./bin/phpunit install
 
 script:
-  # there's no need to load data fixtures before running tests because the project
-  # repository already includes a test database with all the fixtures needed to run the tests
+  # There's no need to load data fixtures before running tests because the project
+  # repository already includes a test database with all the fixtures needed to run the tests.
   - ./bin/phpunit
-  # this checks that the source code follows the Symfony Code Syntax rules
+  # This checks that the source code follows the Symfony Code Syntax rules.
   - '[[ "$TRAVIS_PHP_VERSION" == "7.4" ]] || ./vendor/bin/php-cs-fixer fix --diff --dry-run -v'
-  # this checks that the YAML config files contain no syntax errors
+  # This checks that the YAML config files contain no syntax errors.
   - ./bin/console lint:yaml config --parse-tags
-  # this checks that the Twig template files contain no syntax errors
+  # This checks that the Twig template files contain no syntax errors.
   - ./bin/console lint:twig templates --env=prod
-  # this checks that the XLIFF translations contain no syntax errors
+  # This checks that the XLIFF translations contain no syntax errors.
   - ./bin/console lint:xliff translations
-  # this checks that arguments injected into services match type declarations
+  # This checks that arguments injected into services match type declarations.
   - ./bin/console lint:container
-  # TODO: replace the old security checker by the new checker provided by the 'symfony' binary
-  # this checks that the application doesn't use dependencies with known security vulnerabilities
-  #- ./bin/console security:check
-  # this checks that Doctrine's mapping configurations are valid
+  # This checks that the application doesn't use dependencies with known security vulnerabilities.
+  - symfony check:security
+  # This checks that Doctrine's mapping configurations are valid.
   - ./bin/console doctrine:schema:validate --skip-sync -vvv --no-interaction
-  #  Fail CI if the repo is in a dirty state after building assets (only for current release ie install)
+  # Fail CI if the repo is in a dirty state after building assets (only for current release ie install).
   #-  if [[ "$ACTION" == "install" ]]; then yarn install && yarn encore production && git add --all && git diff --staged --exit-code; fi
   - composer validate --strict