1 files changed, 17 insertions, 0 deletions

diff --git a/test/src/casefiddle-tests.el b/test/src/casefiddle-tests.el
index ed9a2f93306..54793f2cda4 100644
--- a/test/src/casefiddle-tests.el
+++ b/test/src/casefiddle-tests.el
@@ -259,5 +259,22 @@
       (should (eq tc (capitalize ch)))
       (should (eq tc (upcase-initials ch))))))
 
+(defvar casefiddle-oldfunc region-extract-function)
+
+(defun casefiddle-loopfunc (method)
+  (if (eq method 'bounds)
+      (let ((looping (list '(1 . 1))))
+        (setcdr looping looping))
+    (funcall casefiddle-oldfunc method)))
+
+(defun casefiddle-badfunc (method)
+  (if (eq method 'bounds)
+      '(())
+    (funcall casefiddle-oldfunc method)))
+
+(ert-deftest casefiddle-invalid-region-extract-function ()
+  (dolist (region-extract-function '(casefiddle-badfunc casefiddle-loopfunc))
+    (with-temp-buffer
+      (should-error (upcase-region nil nil t)))))
 
 ;;; casefiddle-tests.el ends here