Add an expensive test for defcustom types

* admin/cus-test.el (cus-test-opts): Return the tests.

* test/lisp/custom-tests.el (check-for-wrong-custom-types): Test
custom types (bug#30990).

1 files changed, 8 insertions, 3 deletions

diff --git a/admin/cus-test.el b/admin/cus-test.el
index 842240946eb..cee8c19ba12 100644
--- a/admin/cus-test.el
+++ b/admin/cus-test.el
@@ -370,7 +370,9 @@ This function is suitable for batch mode.  E.g., invoke
 
 in the Emacs source directory.
 Normally only tests options belonging to files in loaddefs.el.
-If optional argument ALL is non-nil, test all files with defcustoms."
+If optional argument ALL is non-nil, test all files with defcustoms.
+
+Returns a list of variables with suspicious types."
   (interactive)
   (and noninteractive
        command-line-args-left
@@ -382,9 +384,12 @@ If optional argument ALL is non-nil, test all files with defcustoms."
   (message "Running %s" 'cus-test-apropos)
   (cus-test-apropos "")
   (if (not cus-test-errors)
-      (message "No problems found")
+      (progn
+        (message "No problems found")
+        nil)
     (message "The following options might have problems:")
-    (cus-test-message cus-test-errors)))
+    (cus-test-message cus-test-errors)
+    cus-test-errors))
 
 (defun cus-test-deps ()
   "Run a verbose version of `custom-load-symbol' on all atoms.