Add tests for remote files in auto-revert-tests

* lisp/autorevert.el (auto-revert-debug): New defvar.
(auto-revert-notify-handler): Write traces.

* lisp/filenotify.el (file-notify-debug): New defvar.
(file-notify-handle-event, file-notify-callback): Write traces.

* lisp/net/tramp-sh.el (tramp-sh-handle-vc-registered):
Handle nil `vc-handled-backends'.

* test/lisp/autorevert-tests.el
(auto-revert-test-remote-temporary-file-directory): New defconst.
Handle also $REMOTE_FILE_NOTIFY_LIBRARY.
(auto-revert--test-enabled-remote-checked): New defvar.
(auto-revert--test-enabled-remote): New defun.
(auto-revert--wait-for-revert): Rewrite without timeout.
(auto-revert--deftest-remote): New defmacro.
(auto-revert-test01-auto-revert-several-files):
(auto-revert-test02-auto-revert-deleted-file): Adapt for remote files.
(auto-revert-test02-auto-revert-deleted-file):
Use `auto-revert-debug' for debug messages.
(auto-revert-test00-auto-revert-mode-remote)
(auto-revert-test01-auto-revert-several-files-mode-remote)
(auto-revert-test02-auto-revert-deleted-file-mode-remote)
(auto-revert-test03-auto-revert-tail-mode-mode-remote)
(auto-revert-test04-auto-revert-mode-dired-mode-remote): New tests.

* test/lisp/filenotify-tests.el (file-notify--test-event-handler):
Use `file-notify-debug' for debug messages.

1 files changed, 5 insertions, 2 deletions

diff --git a/lisp/autorevert.el b/lisp/autorevert.el
index cdd8223fffd..7cd5e7ee8bf 100644
--- a/lisp/autorevert.el
+++ b/lisp/autorevert.el
@@ -126,8 +126,6 @@ Global Auto-Revert Mode does so in all buffers."
 
 ;; Variables:
 
-;;; What's this?: ;; Autoload for the benefit of `make-mode-line-mouse-sensitive'.
-;;; What's this?: ;;;###autoload
 (defvar auto-revert-mode nil
   "Non-nil when Auto-Revert Mode is active.
 Never set this variable directly, use the command `auto-revert-mode' instead.")
@@ -365,6 +363,9 @@ buffer.")
   "Non-nil when file has been modified on the file system.
 This has been reported by a file notification event.")
 
+(defvar auto-revert-debug nil
+  "Use for debug messages.")
+
 ;; Functions:
 
 (defun auto-revert-remove-current-buffer (&optional buffer)
@@ -634,6 +635,8 @@ system.")
       ;; Since we watch a directory, a file name must be returned.
       (cl-assert (stringp file))
       (when (eq action 'renamed) (cl-assert (stringp file1)))
+      (when auto-revert-debug
+        (message "auto-revert-notify-handler %S" event))
 
       (if (eq action 'stopped)
           ;; File notification has stopped.  Continue with polling.