The tests/libtest directory is missing from the .dir-locals.el, so the
emacs flycheck would not work for the unit tests. Add it to the
configuration.
(cherry picked from commit
80fbd849d57c41a3c06f384512645ee1eced72ae)
(expand-file-name
(concat directory-of-current-dir-locals-file "lib/bind9/include"))
+ ;; libtest
+ (expand-file-name
+ (concat directory-of-current-dir-locals-file "tests/include"))
+
;; bin
(expand-file-name
(concat directory-of-current-dir-locals-file "bin/check"))