bug#30807: Tramp tests take waaayyy too long and refuse to exit

[Michael Albinus]

Paul Eggert <eggert@cs.ucla.edu> writes:

Hi Paul,

> Thanks, I did a 'git pull' and a 'make bootstrap' followed by a 'make
> check' and got better numbers. Here are the top four now:
>
> tramp-test21-file-links (9.909445 sec)
> cl-seq-test-bug24264 (12.105374 sec)
> tramp-test38-special-characters (13.106871 sec)
> auto-revert-test00-auto-revert-mode (13.113220 sec)

I've profiled tramp-tests.el, and could optimize some of the
tests. Surprisingly, should-error clauses take much more time than other
forms.

Furthermore, there was an error in how tramp-tests determine whether
expensive tests run. This I've fixed as well.

As a result, I have now

   passed  13/42  tramp-test11-copy-file (1.050841 sec)
   passed  14/42  tramp-test12-rename-file (1.175471 sec)
   passed  25/42  tramp-test21-file-links (0.606194 sec)
   passed  36/42  tramp-test38-special-characters (0.535814 sec)

Ran 42 tests, 41 results as expected, 1 skipped (2018-03-17 15:49:10+0100, 
13.198513 sec)

The high runners take less time, and the whole duration for tramp-tests
is 13 sec. This is acceptable, isn't it?

I will continue to analyze other long-running tests I feel responsible
(autorevert-tests, filenotify-tests), but for this bug report I believe
we could close it.

Best regards, Michael.