diff --git a/src/emacs/test/lean-option-test.el b/src/emacs/test/lean-option-test.el
new file mode 100644
index 000000000..2b6d9a5ee
--- /dev/null
+++ b/src/emacs/test/lean-option-test.el
@@ -0,0 +1,18 @@
+;; Copyright (c) 2014 Microsoft Corporation. All rights reserved.
+;; Released under Apache 2.0 license as described in the file LICENSE.
+;;
+;; Author: Soonho Kong
+;;
+
+(require 'ert)
+(require 'lean-option)
+
+(ert-deftest lean-test-update-string-alist ()
+  (lean-update-option-alist "pp::implicit" 'true)
+  (should
+   (equal (assoc-string "pp::implicit" lean-global-option-alist)
+          '("pp::implicit" . true)))
+  (lean-update-option-alist "pp::implicit" 'false)
+  (should
+   (equal (assoc-string "pp::implicit" lean-global-option-alist)
+          '("pp::implicit" . false))))