Allow Symfony 4 components, and test on all three versions of Symfony.

.gitignore

@@ -47,4 +47,4 @@
 # Backup entities generated with doctrine:generate:entities command
 */Entity/*~
 
-.idea
+.idea

.travis.yml

@@ -1,36 +1,39 @@
 language: php
 
+branches:
+  # Only test the master branch and SemVer tags.
+  only:
+    - master
+    - /^[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+.*$/
+
 matrix:
   fast_finish: true
   include:
+    - php: 7.2
+      env: 'SCENARIO=symfony4 HIGHEST_LOWEST="update"'
     - php: 7.1
-      env: dependencies=highest
-    - php: 7.1
-    - php: 7.0
+      env: 'SCENARIO=symfony4'
+    - php: 7.0.11
+      env: 'HIGHEST_LOWEST="update"'
+    - php: 7.0.11
     - php: 5.6
     - php: 5.5
-      env: dependencies=lowest
     - php: 5.4
-      env: dependencies=lowest
+      env: 'SCENARIO=symfony2 HIGHEST_LOWEST="update --prefer-lowest'
+
+sudo: false
 
 cache:
   apt: true
   directories:
   - "$HOME/.composer/cache"
   - "vendor"
 
-before_install:
-  - composer selfupdate
-
 install:
-  # Load composer dependencies.
-  - composer validate --no-check-all --ansi
-  - if [ -z "$dependencies" ]; then composer install --prefer-dist --optimize-autoloader -n; fi;
-  - if [ "$dependencies" = "lowest" ]; then composer update --prefer-dist --prefer-lowest --optimize-autoloader -n; fi;
-  - if [ "$dependencies" = "highest" ]; then composer update --prefer-dist --optimize-autoloader -n; fi;
+  - 'composer scenario "${SCENARIO}" "${HIGHEST_LOWEST-install}"'
 
 script:
-  - ./scripts/run-tests.sh
+  - composer test
 
 after_success:
-  - ./vendor/bin/coveralls -vvv
+  - travis_retry php vendor/bin/coveralls -v

composer.json

@@ -4,7 +4,7 @@
     "type": "library",
     "require": {
         "php": ">=5.4",
-        "symfony/yaml":                   "^2.8.11|^3",
+        "symfony/yaml":                   "^2.8.11|^3|^4",
         "dflydev/dot-access-data":        "^1.1.0"
     },
     "license": "MIT",
@@ -13,17 +13,43 @@
             "name": "Matthew Grasmick"
         }
     ],
-    "minimum-stability": "dev",
-    "prefer-stable": true,
+    "minimum-stability": "stable",
     "autoload": {
         "psr-4": {
             "Grasmash\\YamlExpander\\":        "src/"
         }
     },
     "require-dev": {
-        "squizlabs/php_codesniffer":      "^2.7",
-        "phpunit/phpunit":                "^4.8|^5.5.4",
-        "satooshi/php-coveralls": "^1.0"
+        "phpunit/phpunit": "^4.8|^5.5.4",
+        "satooshi/php-coveralls": "^1.0.2|dev-master",
+        "greg-1-anderson/composer-test-scenarios": "^1",
+        "squizlabs/php_codesniffer": "^2.7"
+    },
+    "scripts": {
+        "cs": "phpcs -n --standard=PSR2 src tests --exclude=Generic.Files.LineLength",
+        "cbf": "phpcbf -n --standard=PSR2 src tests --exclude=Generic.Files.LineLength",
+        "unit": "phpunit",
+        "lint": [
+            "find src -name '*.php' -print0 | xargs -0 -n1 php -l",
+            "find tests -name '*.php' -print0 | xargs -0 -n1 php -l"
+        ],
+        "test": [
+            "@lint",
+            "@unit",
+            "@cs"
+        ],
+        "scenario": "scenarios/install",
+        "post-update-cmd": [
+            "create-scenario symfony4 'symfony/console:^4.0'",
+            "create-scenario symfony2 'symfony/console:^2.8' --platform-php '5.4' --no-lockfile"
+        ]
+    },
+    "config": {
+        "optimize-autoloader": true,
+        "sort-packages": true,
+        "platform": {
+            "php": "5.5.9"
+        }
     },
     "extra": {
         "branch-alias": {