Emacs js2-mode hook - Avoid "Code has no side effect" warnings in tests using chaijs

rr-js2.el

;; Get rid of extraneous warnings from js2-mode when using chai test library, e.g.
;;          expect(o.loaded).to.be.false;
;; triggers "Code has no side effect"
;;
;; This is just a workaround: such messages will be removed for the whole file.

(defun rr-js2-tests-filter-warnings ()
  (setq js2-parsed-warnings
        (let (rslt)
          (dolist (e js2-parsed-warnings (reverse rslt))
            (when (not (string= (caar e) "msg.no.side.effects"))
              (setq rslt (cons (caar e) rslt))
              ))
          ))
  )

(add-hook 'js2-mode-hook
          (lambda ()
          (when (or
                 (string-match-p "/tests?/.*\\.js$" (buffer-file-name))
                 (string-match-p "\\.spec\\.js$" (buffer-file-name))
                 ))
          (add-hook 'js2-post-parse-callbacks 'rr-js2-tests-filter-warnings)
          )
)

Very nice, thank you!