Check composer requirements on Travis

Author: lookyman

.travis.yml

@@ -11,5 +11,8 @@ before_script:
   - if [ "$dependencies" = "highest" ]; then composer update --no-interaction; fi;
 script:
   - vendor/bin/phing
+  - >
+    wget https://github.com/maglnet/ComposerRequireChecker/releases/download/0.2.1/composer-require-checker.phar
+    && php composer-require-checker.phar check composer.json
 after_script:
   - php vendor/bin/coveralls -v

composer.json

@@ -18,6 +18,7 @@
   },
   "require": {
     "php": "^7.1",
+    "ext-simplexml": "*",
     "phpstan/phpstan": "^0.10",
     "nikic/php-parser": "^4.0"
   },