Require fully qualified function calls

.travis.yml

@@ -18,6 +18,7 @@ before_script:
 
 script:
   - phpdbg -qrr vendor/bin/phpunit --coverage-text --coverage-clover build/logs/clover.xml
+  - php vendor/bin/fqn-check lib
   - php vendor/bin/php-cs-fixer --diff --dry-run -v fix
 
 after_script:

composer.json

@@ -8,7 +8,8 @@
     "require-dev": {
         "amphp/loop": "dev-master",
         "phpunit/phpunit": "^5.0",
-        "friendsofphp/php-cs-fixer": "~1.9"
+        "friendsofphp/php-cs-fixer": "~1.9",
+        "kelunik/fqn-check": "^0.1.3"
     },
     "license": "MIT",
     "authors": [
@@ -26,4 +27,4 @@
             "Amp\\Process\\": "lib"
         }
     }
-}
+}