diff --git a/tests/UnitTests/TemplateSource/TagTests/Assign/PHPunitplugins/function.checkvar.php b/tests/UnitTests/TemplateSource/TagTests/Assign/PHPunitplugins/function.checkvar.php
new file mode 100644
index 00000000..08375bc7
--- /dev/null
+++ b/tests/UnitTests/TemplateSource/TagTests/Assign/PHPunitplugins/function.checkvar.php
@@ -0,0 +1,44 @@
+<?php
+/**
+ * Smarty plugin for testing scopes
+ *
+ * @package    Smarty
+ * @subpackage PHPunitPlugin
+ */
+
+/**
+ * Smarty {checkvar}
+ *
+ * @param array $params parameter array
+ * @param object $template template object
+ *
+ * @return string
+ */
+function smarty_function_checkvar($params, $template)
+{
+    $output = '';
+    $var = $params['var'];
+    $ptr = $template;
+    while ($ptr) {
+        if ($ptr instanceof Smarty_Internal_Template) {
+            $output .= "template {$ptr->source->name}:var =";
+            $output .= isset($ptr->tpl_vars[$var]) ? $ptr->tpl_vars[$var] : 'null';
+            $output .= "\n";
+            $ptr = $ptr->parent;
+        } elseif ($ptr instanceof Smarty_Data) {
+            $output .= "data:var =";
+            $output .= isset($ptr->tpl_vars[$var]) ? $ptr->tpl_vars[$var] : 'null';
+            $output .= "\n";
+            $ptr = $ptr->parent;
+        } else {
+            $ptr = null;
+        }
+    }
+    $output .= "Smarty:var =";
+    $output .= isset($template->smarty->tpl_vars[$var]) ? $template->smarty->tpl_vars[$var] : 'null';
+    $output .= "\n";
+    $output .= "global:var =";
+    $output .= isset(Smarty::$global_tpl_vars[$var]) ? Smarty::$global_tpl_vars[$var] : 'null';
+    $output .= "\n";
+    return $output;
+}