Add more comments, refs composer#12445

Author: Seldaek

tests/Composer/Test/InstallerTest.php

@@ -372,6 +372,7 @@ private function doTestIntegration(string $file, string $message, ?string $condi
 
             return $installer->run();
         });
+        // Compatibility layer for symfony/console <7.4
         method_exists($application, 'addCommand') ? $application->addCommand($install) : $application->add($install);
 
         $update = new Command('update');
@@ -420,6 +421,7 @@ private function doTestIntegration(string $file, string $message, ?string $condi
 
             return $installer->run();
         });
+        // Compatibility layer for symfony/console <7.4
         method_exists($application, 'addCommand') ? $application->addCommand($update) : $application->add($update);
 
         if (!Preg::isMatch('{^(install|update)\b}', $run)) {