2 files changed, 18 insertions, 42 deletions

diff --git a/test/lisp/emacs-lisp/ert-tests.el b/test/lisp/emacs-lisp/ert-tests.el
index e92b4342748..cb957bd9fd6 100644
--- a/test/lisp/emacs-lisp/ert-tests.el
+++ b/test/lisp/emacs-lisp/ert-tests.el
@@ -496,48 +496,6 @@ This macro is used to test if macroexpansion in `should' works."
 
 
 ;;; Tests for utility functions.
-(ert-deftest ert-test-proper-list-p ()
-  (should (ert--proper-list-p '()))
-  (should (ert--proper-list-p '(1)))
-  (should (ert--proper-list-p '(1 2)))
-  (should (ert--proper-list-p '(1 2 3)))
-  (should (ert--proper-list-p '(1 2 3 4)))
-  (should (not (ert--proper-list-p 'a)))
-  (should (not (ert--proper-list-p '(1 . a))))
-  (should (not (ert--proper-list-p '(1 2 . a))))
-  (should (not (ert--proper-list-p '(1 2 3 . a))))
-  (should (not (ert--proper-list-p '(1 2 3 4 . a))))
-  (let ((a (list 1)))
-    (setf (cdr (last a)) a)
-    (should (not (ert--proper-list-p a))))
-  (let ((a (list 1 2)))
-    (setf (cdr (last a)) a)
-    (should (not (ert--proper-list-p a))))
-  (let ((a (list 1 2 3)))
-    (setf (cdr (last a)) a)
-    (should (not (ert--proper-list-p a))))
-  (let ((a (list 1 2 3 4)))
-    (setf (cdr (last a)) a)
-    (should (not (ert--proper-list-p a))))
-  (let ((a (list 1 2)))
-    (setf (cdr (last a)) (cdr a))
-    (should (not (ert--proper-list-p a))))
-  (let ((a (list 1 2 3)))
-    (setf (cdr (last a)) (cdr a))
-    (should (not (ert--proper-list-p a))))
-  (let ((a (list 1 2 3 4)))
-    (setf (cdr (last a)) (cdr a))
-    (should (not (ert--proper-list-p a))))
-  (let ((a (list 1 2 3)))
-    (setf (cdr (last a)) (cddr a))
-    (should (not (ert--proper-list-p a))))
-  (let ((a (list 1 2 3 4)))
-    (setf (cdr (last a)) (cddr a))
-    (should (not (ert--proper-list-p a))))
-  (let ((a (list 1 2 3 4)))
-    (setf (cdr (last a)) (cl-cdddr a))
-    (should (not (ert--proper-list-p a)))))
-
 (ert-deftest ert-test-parse-keys-and-body ()
   (should (equal (ert--parse-keys-and-body '(foo)) '(nil (foo))))
   (should (equal (ert--parse-keys-and-body '(:bar foo)) '((:bar foo) nil)))
diff --git a/test/lisp/subr-tests.el b/test/lisp/subr-tests.el
index 52b61d9fb97..86938d5dbe0 100644
--- a/test/lisp/subr-tests.el
+++ b/test/lisp/subr-tests.el
@@ -306,6 +306,24 @@ cf. Bug#25477."
   (should (eq (string-to-char (symbol-name (gensym))) ?g))
   (should (eq (string-to-char (symbol-name (gensym "X"))) ?X)))
 
+(ert-deftest subr-tests--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")))))
+
 (ert-deftest subr-tests--assq-delete-all ()
   "Test `assq-delete-all' behavior."
   (cl-flet ((new-list-fn