diff --git a/tests/Common.php b/tests/Common.php
index 5008660..ca5d756 100644
--- a/tests/Common.php
+++ b/tests/Common.php
@@ -95,4 +95,42 @@ abstract class Common extends TestCase {
             $_SERVER['HTTPS'] = null;               // forced
         }
     }
+
+    /**
+     * save previous $_SERVER in $GLOBALS if existing
+     */
+    public function saveSERVER()
+    {
+        if (!isset($GLOBALS['savedSERVER'])){
+            $GLOBALS['savedSERVER'] = [
+                'saved' => false,
+                'value' => null
+            ];
+        }
+        if (!$GLOBALS['savedSERVER']['saved']){
+            if (!isset($_SERVER)){
+                $GLOBALS['savedSERVER']['value'] = null;
+                $GLOBALS['savedSERVER']['saved'] = true;
+            } else {
+                $GLOBALS['savedSERVER']['value'] = $_SERVER;
+                $GLOBALS['savedSERVER']['saved'] = true;
+            }
+        }
+    }
+
+    /**
+     * revert previous $_SERVER in $GLOBALS if existing
+     */
+    public function revertSERVER()
+    {
+        if (isset($GLOBALS['savedSERVER']['saved']) && $GLOBALS['savedSERVER']['saved']){
+            if (is_null($GLOBALS['savedSERVER']['value'])){
+                unset($_SERVER);
+            } else {
+                $_SERVER = $GLOBALS['savedSERVER']['value'];
+            }
+            $GLOBALS['savedSERVER']['saved'] = false;
+            $GLOBALS['savedSERVER']['value'] = null;
+        }
+    }
 }
\ No newline at end of file