Re: ert buffer isolation

[Michael Albinus]

Daniil Iaitskov <dyaitskov@gmail.com> writes:

> Hi Dev list,

Hi Daniil,

> I wrote a few tests with ert package and noticed that buffers opened
> inside ert-deftest
>
> escape the test scope and stay alive.
>
> It affects other tests e.g. find-file creates a buffer with a suffixed
> name if a buffer
>
> with name of file is already exist.
>
> I spent more time on debugging because of this.
>
> Test guidelines recommend tests should not influence each other.
>
> So I suggest by default to wrap test body of ert-deftest with:
>
> (defun scope-buffers (cb)
>   "Kill all buffers created by CB."
>   (let ((existed-buffers (buffer-list)))
>     (unwind-protect (funcall cb)
>       (mapc (lambda (b)
>               (when (not (cl-find b existed-buffers))
>                 (message "Kill buffer [%s]" b)
>                 (kill-buffer b)))
>             (buffer-list)))))

I disagree. ERT test writers shall care of cleanup, so a recommended
template is

--8<---------------cut here---------------start------------->8---
(ert-deftest name ()
  "Doc."
  (let (buffer tmp-file)
    (unwind-protect
        (progn BODY)
      ;; Cleanup.
      (ignore-errors (kill-buffer buffer))
      (ignore-errors (delete-file tmp-file)))))
--8<---------------cut here---------------end--------------->8---

Alternatively, we could extend ert-kill-all-test-buffers from ert-x.el
(or write a new function), which would be called in the Cleanup section.

Would you like to provide a patch along these ideas?

> Best regards,
>
> Daniil Iaitskov

Best regards, Michael.