added the new Composer exclude-from-classmap option

Author: annesosensio

composer.json

@@ -28,7 +28,10 @@
         "symfony/proxy-manager-bridge": "Generate service proxies to lazy load them"
     },
     "autoload": {
-        "psr-0": { "Symfony\\Component\\DependencyInjection\\": "" }
+        "psr-0": { "Symfony\\Component\\DependencyInjection\\": "" },
+        "exclude-from-classmap": [
+            "/Tests/"
+        ]
     },
     "target-dir": "Symfony/Component/DependencyInjection",
     "minimum-stability": "dev",