added $installer->isDryRun()

src/Composer/Installer.php

@@ -1052,6 +1052,16 @@ class Installer
         return $this;
     }
 
+    /**
+     * Checks, if this is a dry run (simulation mode).
+     *
+     * @return bool
+     */
+    public function isDryRun()
+    {
+        return $this->dryRun;
+    }
+
     /**
      * prefer source installation
      *