1 files changed, 18 insertions, 0 deletions

diff --git a/test/src/fns-tests.el b/test/src/fns-tests.el
index d6cc99e8e33..6ebab4287f7 100644
--- a/test/src/fns-tests.el
+++ b/test/src/fns-tests.el
@@ -648,4 +648,22 @@
           (should (equal (list (eq a b) n len)
                          (list t n len))))))))
 
+(ert-deftest test-proper-list-p ()
+  "Test `proper-list-p' behavior."
+  (dotimes (length 4)
+    ;; Proper and dotted lists.
+    (let ((list (make-list length 0)))
+      (should (= (proper-list-p list) length))
+      (should (not (proper-list-p (nconc list 0)))))
+    ;; Circular lists.
+    (dotimes (n (1+ length))
+      (let ((circle (make-list (1+ length) 0)))
+        (should (not (proper-list-p (nconc circle (nthcdr n circle))))))))
+  ;; Atoms.
+  (should (not (proper-list-p 0)))
+  (should (not (proper-list-p "")))
+  (should (not (proper-list-p [])))
+  (should (not (proper-list-p (make-bool-vector 0 nil))))
+  (should (not (proper-list-p (make-symbol "a")))))
+
 (provide 'fns-tests)