Subject: Re: [PATCH v3] Don't rewrite buffer contents after saving by rename

From: Michael Albinus <[email-masked]>
Date: Thu, 02 May 2019 13:50:56 +0200

Jonathan Tomer <[email-masked]> writes:

Hi Jonathan,

> +(ert-deftest tramp-test46-file-precious-flag ()

Since this belongs rather to write-region, I would call it
`tramp-test10-write-region-file-precious-flag', and move it to the
repsective place in file.

> +  "Check that file-precious-flag is respected with Tramp in use."
> +  (let* ((temp-file (make-temp-file "emacs"))
> +         (remote-file (concat "/mock:localhost:" temp-file))

Please don't do this. The mock method does not work everywhere, for
example on an MS Windows machine.

`file-precious-flag' is handled in the tramp-sh.el handler only. So you
might start with the test `tramp--test-sh-p', and skip otherwise.

And then you could use the same mechanism like in the other
tests. Something like this:

--8<---------------cut here---------------start------------->8---
(ert-deftest tramp-test10-write-region-file-precious-flag ()
  "Check that `file-precious-flag' is respected with Tramp in use."
  (skip-unless (tramp--test-enabled))
  (skip-unless (tramp--test-sh-p))

  (let ((tmp-name (tramp--test-make-temp-name))
	(advice (lambda (_start _end filename &rest r)
		  (should-not (string= filename tmp-name)))))

    (unwind-protect
        (with-current-buffer (find-file-noselect tmp-name)
	  ;; Write initial contents.  Adapt `visited-file-modtime'
	  ;; in order to suppress confirmation.
	  (insert "foo")
	  (write-region nil nil tmp-name)
          (set-visited-file-modtime)
	  ;; Run the test.
          (advice-add 'write-region :before advice)
          (setq-local file-precious-flag t)
          (insert "bar")
          (should (null (save-buffer))))

      ;; Cleanup.
      (ignore-errors (advice-remove 'write-region advice))
      (ignore-errors (delete-file tmp-name)))))
--8<---------------cut here---------------end--------------->8---

I haven't tested further, this gives an error for me. Don't know yet,
whether it is the test definition, or (more likely) a problem in Tramp.

Best regards, Michael.