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.

5 files changed, 237 insertions, 105 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.
diff --git a/lisp/filenotify.el b/lisp/filenotify.el
index 4d22061138f..a6054c175f1 100644
--- a/lisp/filenotify.el
+++ b/lisp/filenotify.el
@@ -30,6 +30,9 @@
 (require 'cl-lib)
 (eval-when-compile (require 'subr-x))
 
+(defvar file-notify-debug nil
+  "Use for debug messages.")
+
 (defconst file-notify--library
   (cond
    ((featurep 'inotify) 'inotify)
@@ -93,7 +96,8 @@ If EVENT is a filewatch event, call its callback.  It has the format
 
 Otherwise, signal a `file-notify-error'."
   (interactive "e")
-  ;;(message "file-notify-handle-event %S" event)
+  (when file-notify-debug
+    (message "file-notify-handle-event %S" event))
   (if (and (consp event)
            (eq (car event) 'file-notify)
            (>= (length event) 3))
@@ -242,11 +246,12 @@ EVENT is the cadr of the event in `file-notify-handle-event'
                            (string-equal
                             (file-notify--watch-filename watch)
                             (file-name-nondirectory file1)))))
-            ;;(message
-            ;;"file-notify-callback %S %S %S %S %S %S %S"
-            ;;desc action file file1 watch
-            ;;(file-notify--event-watched-file event)
-            ;;(file-notify--watch-directory watch))
+            (when file-notify-debug
+              (message
+               "file-notify-callback %S %S %S %S %S %S %S"
+               desc action file file1 watch
+               (file-notify--event-watched-file event)
+               (file-notify--watch-directory watch)))
             (funcall (file-notify--watch-callback watch)
                      (if file1
                          `(,desc ,action ,file ,file1)
diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index dc64726e211..37ff14a5eb2 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -3444,88 +3444,89 @@ the result will be a local, non-Tramp, file name."
 ;; any other remote command.
 (defun tramp-sh-handle-vc-registered (file)
   "Like `vc-registered' for Tramp files."
-  (with-temp-message ""
-    (with-parsed-tramp-file-name file nil
-      (with-tramp-progress-reporter
-          v 3 (format-message "Checking `vc-registered' for %s" file)
-
-        ;; There could be new files, created by the vc backend.  We
-        ;; cannot reuse the old cache entries, therefore.  In
-        ;; `tramp-get-file-property', `remote-file-name-inhibit-cache'
-        ;; could also be a timestamp as `current-time' returns.  This
-        ;; means invalidate all cache entries with an older timestamp.
-        (let (tramp-vc-registered-file-names
-              (remote-file-name-inhibit-cache (current-time))
-              (file-name-handler-alist
-               `((,tramp-file-name-regexp . tramp-vc-file-name-handler))))
-
-          ;; Here we collect only file names, which need an operation.
-          (tramp-with-demoted-errors
-              v "Error in 1st pass of `vc-registered': %s"
-            (tramp-run-real-handler #'vc-registered (list file)))
-          (tramp-message v 10 "\n%s" tramp-vc-registered-file-names)
-
-          ;; Send just one command, in order to fill the cache.
-          (when tramp-vc-registered-file-names
-            (tramp-maybe-send-script
-             v
-             (format tramp-vc-registered-read-file-names
-                     (tramp-get-file-exists-command v)
-                     (format "%s -r" (tramp-get-test-command v)))
-             "tramp_vc_registered_read_file_names")
-
-            (dolist
-                (elt
-                 (ignore-errors
-                   ;; We cannot use `tramp-send-command-and-read',
-                   ;; because this does not cooperate well with
-                   ;; heredoc documents.
-                   (tramp-send-command
-                    v
-                    (format
-                     "tramp_vc_registered_read_file_names <<'%s'\n%s\n%s\n"
-                     tramp-end-of-heredoc
-                     (mapconcat #'tramp-shell-quote-argument
-                                tramp-vc-registered-file-names
-                                "\n")
-                     tramp-end-of-heredoc))
-                   (with-current-buffer (tramp-get-connection-buffer v)
-                     ;; Read the expression.
-                     (goto-char (point-min))
-                     (read (current-buffer)))))
-
-              (tramp-set-file-property
-               v (car elt) (cadr elt) (cadr (cdr elt))))))
-
-        ;; Second run.  Now all `file-exists-p' or `file-readable-p'
-        ;; calls shall be answered from the file cache.  We unset
-        ;; `process-file-side-effects' and `remote-file-name-inhibit-cache'
-        ;; in order to keep the cache.
-        (let ((vc-handled-backends vc-handled-backends)
-              remote-file-name-inhibit-cache process-file-side-effects)
-          ;; Reduce `vc-handled-backends' in order to minimize process calls.
-          (when (and (memq 'Bzr vc-handled-backends)
-                     (boundp 'vc-bzr-program)
-                     (not (with-tramp-connection-property v vc-bzr-program
-                            (tramp-find-executable
-                             v vc-bzr-program (tramp-get-remote-path v)))))
-            (setq vc-handled-backends (remq 'Bzr vc-handled-backends)))
-          (when (and (memq 'Git vc-handled-backends)
-                     (boundp 'vc-git-program)
-                     (not (with-tramp-connection-property v vc-git-program
-                            (tramp-find-executable
-                             v vc-git-program (tramp-get-remote-path v)))))
-            (setq vc-handled-backends (remq 'Git vc-handled-backends)))
-          (when (and (memq 'Hg vc-handled-backends)
-                     (boundp 'vc-hg-program)
-                     (not (with-tramp-connection-property v vc-hg-program
-                            (tramp-find-executable
-                             v vc-hg-program (tramp-get-remote-path v)))))
-            (setq vc-handled-backends (remq 'Hg vc-handled-backends)))
-          ;; Run.
-          (tramp-with-demoted-errors
-              v "Error in 2nd pass of `vc-registered': %s"
-            (tramp-run-real-handler #'vc-registered (list file))))))))
+  (when vc-handled-backends
+    (with-temp-message ""
+      (with-parsed-tramp-file-name file nil
+        (with-tramp-progress-reporter
+            v 3 (format-message "Checking `vc-registered' for %s" file)
+
+          ;; There could be new files, created by the vc backend.  We
+          ;; cannot reuse the old cache entries, therefore.  In
+          ;; `tramp-get-file-property', `remote-file-name-inhibit-cache'
+          ;; could also be a timestamp as `current-time' returns.  This
+          ;; means invalidate all cache entries with an older timestamp.
+          (let (tramp-vc-registered-file-names
+                (remote-file-name-inhibit-cache (current-time))
+                (file-name-handler-alist
+                 `((,tramp-file-name-regexp . tramp-vc-file-name-handler))))
+
+            ;; Here we collect only file names, which need an operation.
+            (tramp-with-demoted-errors
+                v "Error in 1st pass of `vc-registered': %s"
+              (tramp-run-real-handler #'vc-registered (list file)))
+            (tramp-message v 10 "\n%s" tramp-vc-registered-file-names)
+
+            ;; Send just one command, in order to fill the cache.
+            (when tramp-vc-registered-file-names
+              (tramp-maybe-send-script
+               v
+               (format tramp-vc-registered-read-file-names
+                       (tramp-get-file-exists-command v)
+                       (format "%s -r" (tramp-get-test-command v)))
+               "tramp_vc_registered_read_file_names")
+
+              (dolist
+                  (elt
+                   (ignore-errors
+                     ;; We cannot use `tramp-send-command-and-read',
+                     ;; because this does not cooperate well with
+                     ;; heredoc documents.
+                     (tramp-send-command
+                      v
+                      (format
+                       "tramp_vc_registered_read_file_names <<'%s'\n%s\n%s\n"
+                       tramp-end-of-heredoc
+                       (mapconcat #'tramp-shell-quote-argument
+                                  tramp-vc-registered-file-names
+                                  "\n")
+                       tramp-end-of-heredoc))
+                     (with-current-buffer (tramp-get-connection-buffer v)
+                       ;; Read the expression.
+                       (goto-char (point-min))
+                       (read (current-buffer)))))
+
+                (tramp-set-file-property
+                 v (car elt) (cadr elt) (cadr (cdr elt))))))
+
+          ;; Second run.  Now all `file-exists-p' or `file-readable-p'
+          ;; calls shall be answered from the file cache.  We unset
+          ;; `process-file-side-effects' and `remote-file-name-inhibit-cache'
+          ;; in order to keep the cache.
+          (let ((vc-handled-backends vc-handled-backends)
+                remote-file-name-inhibit-cache process-file-side-effects)
+            ;; Reduce `vc-handled-backends' in order to minimize process calls.
+            (when (and (memq 'Bzr vc-handled-backends)
+                       (boundp 'vc-bzr-program)
+                       (not (with-tramp-connection-property v vc-bzr-program
+                              (tramp-find-executable
+                               v vc-bzr-program (tramp-get-remote-path v)))))
+              (setq vc-handled-backends (remq 'Bzr vc-handled-backends)))
+            (when (and (memq 'Git vc-handled-backends)
+                       (boundp 'vc-git-program)
+                       (not (with-tramp-connection-property v vc-git-program
+                              (tramp-find-executable
+                               v vc-git-program (tramp-get-remote-path v)))))
+              (setq vc-handled-backends (remq 'Git vc-handled-backends)))
+            (when (and (memq 'Hg vc-handled-backends)
+                       (boundp 'vc-hg-program)
+                       (not (with-tramp-connection-property v vc-hg-program
+                              (tramp-find-executable
+                               v vc-hg-program (tramp-get-remote-path v)))))
+              (setq vc-handled-backends (remq 'Hg vc-handled-backends)))
+            ;; Run.
+            (tramp-with-demoted-errors
+                v "Error in 2nd pass of `vc-registered': %s"
+              (tramp-run-real-handler #'vc-registered (list file)))))))))
 
 ;;;###tramp-autoload
 (defun tramp-sh-file-name-handler (operation &rest args)
diff --git a/test/lisp/autorevert-tests.el b/test/lisp/autorevert-tests.el
index 6e8219d238d..d98c11658fe 100644
--- a/test/lisp/autorevert-tests.el
+++ b/test/lisp/autorevert-tests.el
@@ -19,6 +19,33 @@
 
 ;;; Commentary:
 
+;; Some of the tests require access to a remote host files.  Since
+;; this could be problematic, a mock-up connection method "mock" is
+;; used.  Emulating a remote connection, it simply calls "sh -i".
+;; Tramp's file name handlers still run, so this test is sufficient
+;; except for connection establishing.
+
+;; If you want to test a real Tramp connection, set
+;; $REMOTE_TEMPORARY_FILE_DIRECTORY to a suitable value in order to
+;; overwrite the default value.  If you want to skip tests accessing a
+;; remote host, set this environment variable to "/dev/null" or
+;; whatever is appropriate on your system.
+
+;; For the remote file-notify library, Tramp checks for the existence
+;; of a respective command.  The first command found is used.  In
+;; order to use a dedicated one, the environment variable
+;; $REMOTE_FILE_NOTIFY_LIBRARY shall be set, possible values are
+;; "inotifywait", "gio-monitor" and "gvfs-monitor-dir".
+
+;; Local file-notify libraries are auto-detected during Emacs
+;; configuration.  This can be changed with a respective configuration
+;; argument, like
+;;
+;;   --with-file-notification=inotify
+;;   --with-file-notification=kqueue
+;;   --with-file-notification=gfile
+;;   --with-file-notification=w32
+
 ;; A whole test run can be performed calling the command `auto-revert-test-all'.
 
 ;;; Code:
@@ -26,8 +53,14 @@
 (require 'ert)
 (require 'ert-x)
 (require 'autorevert)
-(setq auto-revert-notify-exclude-dir-regexp "nothing-to-be-excluded"
-      auto-revert-stop-on-user-input nil)
+(require 'tramp)
+
+(setq auto-revert-debug nil
+      auto-revert-notify-exclude-dir-regexp "nothing-to-be-excluded"
+      auto-revert-stop-on-user-input nil
+      file-notify-debug nil
+      tramp-verbose 0
+      tramp-message-show-message nil)
 
 (defconst auto-revert--timeout 10
   "Time to wait for a message.")
@@ -35,19 +68,88 @@
 (defvar auto-revert--messages nil
   "Used to collect messages issued during a section of a test.")
 
+;; There is no default value on w32 systems, which could work out of the box.
+(defconst auto-revert-test-remote-temporary-file-directory
+  (cond
+   ((getenv "REMOTE_TEMPORARY_FILE_DIRECTORY"))
+   ((eq system-type 'windows-nt) null-device)
+   (t (add-to-list
+       'tramp-methods
+       '("mock"
+         (tramp-login-program        "sh")
+         (tramp-login-args           (("-i")))
+         (tramp-remote-shell         "/bin/sh")
+         (tramp-remote-shell-args    ("-c"))
+         (tramp-connection-timeout   10)))
+      (add-to-list
+       'tramp-default-host-alist
+       `("\\`mock\\'" nil ,(system-name)))
+      ;; Emacs' Makefile sets $HOME to a nonexistent value.  Needed in
+      ;; batch mode only, therefore.  `temporary-file-directory' might
+      ;; be quoted, so we unquote it just in case.
+      (unless (and (null noninteractive) (file-directory-p "~/"))
+        (setenv "HOME" (file-name-unquote temporary-file-directory)))
+      (format "/mock::%s" temporary-file-directory)))
+  "Temporary directory for Tramp tests.")
+
+;; Filter suppressed remote file-notify libraries.
+(when (stringp (getenv "REMOTE_FILE_NOTIFY_LIBRARY"))
+  (dolist (lib '("inotifywait" "gio-monitor" "gvfs-monitor-dir"))
+    (unless (string-equal (getenv "REMOTE_FILE_NOTIFY_LIBRARY") lib)
+      (add-to-list 'tramp-connection-properties `(nil ,lib nil)))))
+
+(defvar auto-revert--test-enabled-remote-checked nil
+  "Cached result of `auto-revert--test-enabled-remote'.
+If the function did run, the value is a cons cell, the `cdr'
+being the result.")
+
+(defun auto-revert--test-enabled-remote ()
+  "Whether remote file access is enabled."
+  (unless (consp auto-revert--test-enabled-remote-checked)
+    (setq
+     auto-revert--test-enabled-remote-checked
+     (cons
+      t (ignore-errors
+          (and
+           (file-remote-p auto-revert-test-remote-temporary-file-directory)
+           (file-directory-p auto-revert-test-remote-temporary-file-directory)
+           (file-writable-p
+            auto-revert-test-remote-temporary-file-directory))))))
+  ;; Return result.
+  (cdr auto-revert--test-enabled-remote-checked))
+
 (defun auto-revert--wait-for-revert (buffer)
   "Wait until a message reports reversion of BUFFER.
 This expects `auto-revert--messages' to be bound by
 `ert-with-message-capture' before calling."
-  (with-timeout (auto-revert--timeout nil)
-    (while
-        (null (string-match
-               (format-message "Reverting buffer `%s'." (buffer-name buffer))
-               auto-revert--messages))
+  ;; Remote files do not cooperate well with timers.  So we count ourselves.
+  (let ((ct (current-time)))
+    (while (and (< (float-time (time-subtract (current-time) ct))
+                   auto-revert--timeout)
+                (null (string-match
+                       (format-message
+                        "Reverting buffer `%s'\\." (buffer-name buffer))
+                       auto-revert--messages)))
       (if (with-current-buffer buffer auto-revert-use-notify)
           (read-event nil nil 0.1)
         (sleep-for 0.1)))))
 
+(defmacro auto-revert--deftest-remote (test docstring)
+  "Define ert `TEST-remote' for remote files."
+  (declare (indent 1))
+  `(ert-deftest ,(intern (concat (symbol-name test) "-remote")) ()
+     ,docstring
+     :tags '(:expensive-test)
+     (let ((temporary-file-directory
+            auto-revert-test-remote-temporary-file-directory)
+           (auto-revert-remote-files t)
+           (ert-test (ert-get-test ',test))
+           vc-handled-backends)
+       (skip-unless (auto-revert--test-enabled-remote))
+       (tramp-cleanup-connection
+        (tramp-dissect-file-name temporary-file-directory) nil 'keep-password)
+       (funcall (ert-test-body ert-test)))))
+
 (ert-deftest auto-revert-test00-auto-revert-mode ()
   "Check autorevert for a file."
   ;; `auto-revert-buffers' runs every 5".  And we must wait, until the
@@ -93,13 +195,16 @@ This expects `auto-revert--messages' to be bound by
         (kill-buffer buf))
       (ignore-errors (delete-file tmpfile)))))
 
+(auto-revert--deftest-remote auto-revert-test00-auto-revert-mode
+  "Check autorevert for a remote file.")
+
 ;; This is inspired by Bug#21841.
 (ert-deftest auto-revert-test01-auto-revert-several-files ()
   "Check autorevert for several files at once."
   :tags '(:expensive-test)
-  (skip-unless (executable-find "cp"))
+  (skip-unless (executable-find "cp" (file-remote-p temporary-file-directory)))
 
-  (let* ((cp (executable-find "cp"))
+  (let* ((cp (executable-find "cp" (file-remote-p temporary-file-directory)))
          (tmpdir1 (make-temp-file "auto-revert-test" 'dir))
          (tmpdir2 (make-temp-file "auto-revert-test" 'dir))
          (tmpfile1
@@ -139,7 +244,9 @@ This expects `auto-revert--messages' to be bound by
           ;; Strange, that `copy-directory' does not work as expected.
           ;; The following shell command is not portable on all
           ;; platforms, unfortunately.
-          (shell-command (format "%s -f %s/* %s" cp tmpdir2 tmpdir1))
+          (shell-command
+           (format "%s -f %s/* %s"
+                   cp (file-local-name tmpdir2) (file-local-name tmpdir1)))
 
           ;; Check, that the buffers have been reverted.
           (dolist (buf (list buf1 buf2))
@@ -155,6 +262,9 @@ This expects `auto-revert--messages' to be bound by
       (ignore-errors (delete-directory tmpdir1 'recursive))
       (ignore-errors (delete-directory tmpdir2 'recursive)))))
 
+(auto-revert--deftest-remote auto-revert-test01-auto-revert-several-files
+  "Check autorevert for several remote files at once.")
+
 ;; This is inspired by Bug#23276.
 (ert-deftest auto-revert-test02-auto-revert-deleted-file ()
   "Check autorevert for a deleted file."
@@ -185,8 +295,8 @@ This expects `auto-revert--messages' to be bound by
             (add-hook
              'before-revert-hook
              (lambda ()
-               ;; Temporarily.
-               (message "%s deleted" buffer-file-name)
+               (when auto-revert-debug
+                 (message "%s deleted" buffer-file-name))
                (delete-file buffer-file-name))
              nil t)
 
@@ -199,7 +309,9 @@ This expects `auto-revert--messages' to be bound by
             ;; polling.
             (should (string-match "any text" (buffer-string)))
             ;; With w32notify, the 'stopped' events are not sent.
+            ;; Same for remote file name handlers.  Why?
             (or (eq file-notify--library 'w32notify)
+                (file-remote-p temporary-file-directory)
                 (should-not auto-revert-notify-watch-descriptor))
 
             ;; Once the file has been recreated, the buffer shall be
@@ -231,6 +343,9 @@ This expects `auto-revert--messages' to be bound by
         (kill-buffer buf))
       (ignore-errors (delete-file tmpfile)))))
 
+(auto-revert--deftest-remote auto-revert-test02-auto-revert-deleted-file
+  "Check autorevert for a deleted remote file.")
+
 (ert-deftest auto-revert-test03-auto-revert-tail-mode ()
   "Check autorevert tail mode."
   ;; `auto-revert-buffers' runs every 5".  And we must wait, until the
@@ -266,6 +381,9 @@ This expects `auto-revert--messages' to be bound by
       (ignore-errors (kill-buffer buf))
       (ignore-errors (delete-file tmpfile)))))
 
+(auto-revert--deftest-remote auto-revert-test03-auto-revert-tail-mode
+  "Check remote autorevert tail mode.")
+
 (ert-deftest auto-revert-test04-auto-revert-mode-dired ()
   "Check autorevert for dired."
   ;; `auto-revert-buffers' runs every 5".  And we must wait, until the
@@ -314,6 +432,9 @@ This expects `auto-revert--messages' to be bound by
         (kill-buffer buf))
       (ignore-errors (delete-file tmpfile)))))
 
+(auto-revert--deftest-remote auto-revert-test04-auto-revert-mode-dired
+  "Check remote autorevert for dired.")
+
 (defun auto-revert-test-all (&optional interactive)
   "Run all tests for \\[auto-revert]."
   (interactive "p")
diff --git a/test/lisp/filenotify-tests.el b/test/lisp/filenotify-tests.el
index a40dc720786..af2d0b33e08 100644
--- a/test/lisp/filenotify-tests.el
+++ b/test/lisp/filenotify-tests.el
@@ -195,7 +195,8 @@ Return nil when any other file notification watch is still active."
         file-notify--test-events nil
         file-notify--test-monitors nil))
 
-(setq password-cache-expiry nil
+(setq file-notify-debug nil
+      password-cache-expiry nil
       tramp-verbose 0
       tramp-message-show-message nil)
 
@@ -515,8 +516,9 @@ and the event to `file-notify--test-events'."
     (unless (string-match
              (regexp-quote ".#")
              (file-notify--event-file-name file-notify--test-event))
-      ;;(message "file-notify--test-event-handler result: %s event: %S"
-               ;;(null (ert-test-failed-p result)) file-notify--test-event)
+      (when file-notify-debug
+        (message "file-notify--test-event-handler result: %s event: %S"
+                 (null (ert-test-failed-p result)) file-notify--test-event))
       (setq file-notify--test-events
             (append file-notify--test-events `(,file-notify--test-event))
             file-notify--test-results