(require 'ert)

(ert-deftest test-modification-hooks ()
  "Test for bug#30823."
  (let ((check-point nil)
	(ov-delete nil)
	(ov-set nil))
    (with-temp-buffer
      (insert "abc")
      (setq ov-set (make-overlay 1 3))
      (overlay-put ov-set 'modification-hooks
		   (list (lambda (o after &rest _args)
			   (and after (setq check-point t)))))
      (setq ov-delete (make-overlay 1 3))
      (overlay-put ov-delete 'modification-hooks
		   (list (lambda (o after &rest _args)
			   (and (not after) (delete-overlay o)))))
      (goto-char 2)
      (insert "1")
      (should (eq check-point t)))))