bug#26911: 25.2; eshell "cd .." doesn't work correctly with TRAMP

[Eli Zaretskii <eliz@gnu.org>]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: eggert@cs.ucla.edu,  26911@debbugs.gnu.org,  mattiase@acm.org,
>   yegortimoshenko@gmail.com
> Date: Fri, 04 Sep 2020 15:53:09 +0200
> 
> > I did, but most of the tests are skipped.  Can you teach me how to
> > enable them on MS-Windows?  I can use PuTTY to connect to a remote
> > GNU/Linux machine where I have an account, if that is necessary.
> 
> Well, first check whether you can connect the remote host in
> question. Try it interactively:
> 
> C-x C-f /plink:user@host:/tmp
> 
> ("user" and "host" at your taste). The connection shall not require a
> password. Alternatively, if you have created a PuTTy session with name
> "session", you could use instead "/plinkx:session:/tmp".
> 
> Then, according to my MS Windows blurb, run in a CMD window:
> 
> --8<---------------cut here---------------start------------->8---
> > set REMOTE_TEMPORARY_FILE_DIRECTORY=/plink:user@host:/tmp
> > %HOMEPATH%\Desktop\emacs-28.0.50\bin\emacs.exe -Q -batch -L X:\src\tramp\lisp -l X:\src\tramp\test\tramp-tests.el -f ert-run-tests-batch-and-exit
> --8<---------------cut here---------------end--------------->8---

OK, thanks.  This worked.  The results (see below) are mixed, but the
problems seem mostly to have something to do with the remote system,
not with Emacs.

The first 27 tests all passed.  Then things went south, with all the
rest but the last 5 tests failing.  The failures are pretty similar,
and can be divided into the following groups:

  . (file-error "Method `plink' should specify both encoding and decoding command or an scp program")

  . (file-error "Couldn't find command to check if file exists")

  .  (file-error "Tramp failed to connect.  If this happens repeatedly, try `M-x tramp-cleanup-this-connection'")

The last error always followed the penultimate one.  Usually, 3
"failed to connect" errors after each couldn't find command".

Several tests failed with other error messages:

  . Test tramp-test17-insert-directory backtrace:
     signal(wrong-type-argument ("listp sh:"))

  . Test tramp-test32-shell-command-dont-erase-buffer condition:
       (ert-test-failed
        ((should
	  (string-equal "barbaz
   "
		        (buffer-string)))
	 :form
	 (string-equal "barbaz
   " "bar")
	 :value nil))

  . Test tramp-test33-environment-variables condition:
       (ert-test-failed
        ((should
	  (string-equal
	   (format "%s,tramp:%s
   " emacs-version tramp-version)
	   (funcall this-shell-command-to-string "echo ${INSIDE_EMACS:-bla}")))
	 :form
	 (string-equal "28.0.50,tramp:2.5.0-pre
   " "")
	 :value nil))

Finally, the summary:

  Ran 71 tests, 32 results as expected, 28 unexpected, 11 skipped (2020-09-04 17:27:32+0300, 1357.765625 sec)

  28 unexpected results:
     FAILED  tramp-test17-insert-directory
     FAILED  tramp-test18-file-attributes
     FAILED  tramp-test19-directory-files-and-attributes
     FAILED  tramp-test20-file-modes
     FAILED  tramp-test21-file-links
     FAILED  tramp-test22-file-times
     FAILED  tramp-test23-visited-file-modtime
     FAILED  tramp-test26-file-name-completion
     FAILED  tramp-test27-load
     FAILED  tramp-test28-process-file
     FAILED  tramp-test29-start-file-process
     FAILED  tramp-test29-start-file-process-direct-async
     FAILED  tramp-test30-make-process
     FAILED  tramp-test30-make-process-direct-async
     FAILED  tramp-test31-interrupt-process
     FAILED  tramp-test32-shell-command
     FAILED  tramp-test32-shell-command-dont-erase-buffer
     FAILED  tramp-test33-environment-variables
     FAILED  tramp-test34-connection-local-variables
     FAILED  tramp-test34-explicit-shell-file-name
     FAILED  tramp-test35-exec-path
     FAILED  tramp-test35-remote-path
     FAILED  tramp-test36-vc-registered
     FAILED  tramp-test37-make-auto-save-file-name
     FAILED  tramp-test38-find-backup-file-name
     FAILED  tramp-test39-make-nearby-temp-file
     FAILED  tramp-test40-special-characters
     FAILED  tramp-test43-asynchronous-requests

  11 skipped results:
    SKIPPED  tramp-test24-file-acl
    SKIPPED  tramp-test25-file-selinux
    SKIPPED  tramp-test33-environment-variables-and-port-numbers
    SKIPPED  tramp-test40-special-characters-with-ls
    SKIPPED  tramp-test40-special-characters-with-perl
    SKIPPED  tramp-test40-special-characters-with-stat
    SKIPPED  tramp-test41-utf8
    SKIPPED  tramp-test41-utf8-with-ls
    SKIPPED  tramp-test41-utf8-with-perl
    SKIPPED  tramp-test41-utf8-with-stat
    SKIPPED  tramp-test42-file-system-info

What can I do about the failed tests?