emacs: test for advice-add :before, :around, :after

emacs-test-advice-add.el

(defun func-1 () (message "aaa"))            ;; target function

(defun my-func-1-adv ()                         ;; advice function
    (message "before"))

(advice-add 'func-1 :before #'my-func-1-adv)

;(func-1)
;---> before
;---> aaa

(advice-remove 'func-1 #'my-func-1-adv)

;(func-1)
;---> aaa

;; ----------------------------------------------------------------
(defun func (a b c)                 ;; target func
  (message (concat a b c)))

(defun my-adv (orig-fun &rest _)    ;; advice
  (message "-----")
  (apply orig-fun _)
  (message "-----")
  nil)

(advice-add 'func :around #'my-adv)

(func "foo" "bar" "baz")

=>
-----
foobarbaz
-----

;; ----------------------------------------------------------------
(defun func-3 () (message "ccc"))    ;; target function

(defun my-func-3-adv ()       ;; advice function
    (message "after"))

(advice-add 'func-3 :after #'my-func-3-adv)

;(func-3)
;---> ccc
;---> after

;; ----------------------------------------------------------------