my-test.el

;; use-region-p returns nil even though it is mocked using cl-flet
;; why?

(defun bwb-gitlab--get-line-nums ()
  "Return line number(s) if applicable.
If region selected, returns range in url form"
  (if (null (use-region-p))
      (message "use-region-p is nil"))
  (cond ((not (gitlab--viewing-filep)) "")
        ((use-region-p)
         (format "#L%d-%d"
                 (line-number-at-pos (region-beginning))
                 (line-number-at-pos (region-end))))
         (t
          (format "#L%d" (line-number-at-pos (point))))))


(ert-deftest test-gitlab-determine-linenum ()
  :tags '(browse)
  (cl-flet ((use-region-p () t))
    (save-excursion
      (let ((buffer (find-file-noselect gitlab-readme)))      
        (set-buffer buffer)
        (forward-line)
        (forward-line)
        (set-mark-command (point))
        (beginning-of-buffer)
        (should (s-equals? (bwb-gitlab--get-line-nums) "#L1-2"))
        ))))


;; actual result of (bwb-gitlab--get-line-nums) => "#L1"
;; and message "use-region-p" is nil shown