Stronger check for Tramp method

* lisp/net/tramp-gvfs.el (tramp-gvfs-maybe-open-connection):
* lisp/net/tramp-rclone.el (tramp-rclone-maybe-open-connection):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-maybe-open-connection):
Use `tramp-get-connection-name'.

* lisp/net/tramp-sh.el (tramp-sh-handle-make-symbolic-link):
* lisp/net/tramp-smb.el (tramp-smb-handle-make-symbolic-link):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-handle-make-symbolic-link):
Don't check remote TARGET.

* lisp/net/tramp.el (tramp-dissect-file-name): Check for proper method.
(tramp-file-name-for-operation): Take only 2nd argument into
account for file name handler.
(tramp-file-name-handler): Suppress checks for `file-remote-p'.

* test/lisp/net/tramp-archive-tests.el
(tramp-archive-test02-file-name-dissect): Suppress check for wrong
method.

* test/lisp/net/tramp-tests.el (tramp--test-instrument-test-case):
Dump *all* Tramp buffers.
(tramp-test02-file-name-dissect)
(tramp-test02-file-name-dissect-simplified)
(tramp-test02-file-name-dissect-separate): Check also wrong method.
(tramp-test03-file-name-defaults): Check, that the respective
Tramp package is loaded.
(tramp-test04-substitute-in-file-name)
(tramp-test05-expand-file-name)
(tramp-test06-directory-file-name, tramp-test44-auto-load):
Suppress check for wrong method.
(tramp-test30-make-process): Remove instrumentation code.
(tramp-test31-interrupt-process, tramp-test36-vc-registered):
Guarantee that connection is established prior starting process.

8 files changed, 351 insertions, 274 deletions

diff --git a/lisp/net/tramp-gvfs.el b/lisp/net/tramp-gvfs.el
index 38102318240..17c2e79833b 100644
--- a/lisp/net/tramp-gvfs.el
+++ b/lisp/net/tramp-gvfs.el
@@ -1765,7 +1765,7 @@ connection if a previous connection has died for some reason."
   ;; better solution?
   (unless (get-buffer-process (tramp-get-connection-buffer vec))
     (let ((p (make-network-process
-              :name (tramp-buffer-name vec)
+              :name (tramp-get-connection-name vec)
               :buffer (tramp-get-connection-buffer vec)
               :server t :host 'local :service t :noquery t)))
       (process-put p 'vector vec)
diff --git a/lisp/net/tramp-rclone.el b/lisp/net/tramp-rclone.el
index 0148116d739..9e99493cbf6 100644
--- a/lisp/net/tramp-rclone.el
+++ b/lisp/net/tramp-rclone.el
@@ -543,7 +543,7 @@ connection if a previous connection has died for some reason."
       ;; we create a dummy process.  Maybe there is a better solution?
       (unless (get-buffer-process (tramp-get-connection-buffer vec))
         (let ((p (make-network-process
-                  :name (tramp-buffer-name vec)
+                  :name (tramp-get-connection-name vec)
                   :buffer (tramp-get-connection-buffer vec)
                   :server t :host 'local :service t :noquery t)))
           (process-put p 'vector vec)
diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index 2d27baf454a..34fda5af176 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -1027,11 +1027,13 @@ component is used as the target of the symlink."
 
     (with-parsed-tramp-file-name linkname nil
       ;; If TARGET is a Tramp name, use just the localname component.
-      (when (and (tramp-tramp-file-p target)
-                 (tramp-file-name-equal-p v (tramp-dissect-file-name target)))
-        (setq target
-              (tramp-file-name-localname
-               (tramp-dissect-file-name (expand-file-name target)))))
+      ;; Don't check for a proper method.
+      (let ((non-essential t))
+        (when (and (tramp-tramp-file-p target)
+                   (tramp-file-name-equal-p v (tramp-dissect-file-name target)))
+          (setq target
+                (tramp-file-name-localname
+                 (tramp-dissect-file-name (expand-file-name target))))))
 
       ;; If TARGET is still remote, quote it.
       (if (tramp-tramp-file-p target)
diff --git a/lisp/net/tramp-smb.el b/lisp/net/tramp-smb.el
index 9d15c0562bf..84725db2168 100644
--- a/lisp/net/tramp-smb.el
+++ b/lisp/net/tramp-smb.el
@@ -1161,11 +1161,13 @@ component is used as the target of the symlink."
 
     (with-parsed-tramp-file-name linkname nil
       ;; If TARGET is a Tramp name, use just the localname component.
-      (when (and (tramp-tramp-file-p target)
-                 (tramp-file-name-equal-p v (tramp-dissect-file-name target)))
-        (setq target
-              (tramp-file-name-localname
-               (tramp-dissect-file-name (expand-file-name target)))))
+      ;; Don't check for a proper method.
+      (let ((non-essential t))
+        (when (and (tramp-tramp-file-p target)
+                   (tramp-file-name-equal-p v (tramp-dissect-file-name target)))
+          (setq target
+                (tramp-file-name-localname
+                 (tramp-dissect-file-name (expand-file-name target))))))
 
       ;; If TARGET is still remote, quote it.
       (if (tramp-tramp-file-p target)
diff --git a/lisp/net/tramp-sudoedit.el b/lisp/net/tramp-sudoedit.el
index 0d9e04d0bd1..f056e73366e 100644
--- a/lisp/net/tramp-sudoedit.el
+++ b/lisp/net/tramp-sudoedit.el
@@ -607,11 +607,13 @@ component is used as the target of the symlink."
 
     (with-parsed-tramp-file-name linkname nil
       ;; If TARGET is a Tramp name, use just the localname component.
-      (when (and (tramp-tramp-file-p target)
-                 (tramp-file-name-equal-p v (tramp-dissect-file-name target)))
-        (setq target
-              (tramp-file-name-localname
-               (tramp-dissect-file-name (expand-file-name target)))))
+      ;; Don't check for a proper method.
+      (let ((non-essential t))
+        (when (and (tramp-tramp-file-p target)
+                   (tramp-file-name-equal-p v (tramp-dissect-file-name target)))
+          (setq target
+                (tramp-file-name-localname
+                 (tramp-dissect-file-name (expand-file-name target))))))
 
       ;; If TARGET is still remote, quote it.
       (if (tramp-tramp-file-p target)
@@ -780,7 +782,7 @@ connection if a previous connection has died for some reason."
       (throw 'non-essential 'non-essential))
 
     (let ((p (make-network-process
-              :name (tramp-buffer-name vec)
+              :name (tramp-get-connection-name vec)
               :buffer (tramp-get-connection-buffer vec)
               :server t :host 'local :service t :noquery t)))
       (process-put p 'vector vec)
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index a2558184fb4..f6dd6b5866d 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -1435,6 +1435,12 @@ default values are used."
             (setq v (make-tramp-file-name
                      :method method :user user :domain domain :host host
                      :port port :localname localname :hop hop))
+          ;; The method must be known.
+          (unless (or (tramp-completion-mode-p)
+                      (string-equal method tramp-default-method-marker)
+                      (assoc method tramp-methods))
+            (tramp-user-error
+             v "Method `%s' is not known." method))
           ;; Only some methods from tramp-sh.el do support multi-hops.
           (when (and
                  hop
@@ -2175,17 +2181,16 @@ Must be handled by the callers."
     (if (file-name-absolute-p (nth 0 args))
         (nth 0 args)
       default-directory))
+   ;; STRING FILE.
+   ;; Starting with Emacs 26.1, just the 2nd argument of
+   ;; `make-symbolic-link' matters.
+   ((eq operation 'make-symbolic-link) (nth 1 args))
    ;; FILE DIRECTORY resp FILE1 FILE2.
    ((member operation
             '(add-name-to-file copy-directory copy-file
               file-equal-p file-in-directory-p
               file-name-all-completions file-name-completion
-              ;; Starting with Emacs 26.1, just the 2nd argument of
-              ;; `make-symbolic-link' matters.  For backward
-              ;; compatibility, we still accept the first argument as
-              ;; file name to be checked.  Handled properly in
-              ;; `tramp-handle-*-make-symbolic-link'.
-              file-newer-than-file-p make-symbolic-link rename-file))
+              file-newer-than-file-p rename-file))
     (cond
      ((tramp-tramp-file-p (nth 0 args)) (nth 0 args))
      ((tramp-tramp-file-p (nth 1 args)) (nth 1 args))
@@ -2280,7 +2285,10 @@ preventing reentrant calls of Tramp.")
 (defun tramp-file-name-handler (operation &rest args)
   "Invoke Tramp file name handler.
 Falls back to normal file name handler if no Tramp file name handler exists."
-  (let ((filename (apply #'tramp-file-name-for-operation operation args)))
+  (let ((filename (apply #'tramp-file-name-for-operation operation args))
+        ;; `file-remote-p' is called for everything, even for symbolic
+        ;; links which look remote.  We don't want to get an error.
+        (non-essential (or non-essential (eq operation 'file-remote-p))))
     (if (tramp-tramp-file-p filename)
         (save-match-data
           (setq filename (tramp-replace-environment-variables filename))
diff --git a/test/lisp/net/tramp-archive-tests.el b/test/lisp/net/tramp-archive-tests.el
index 454279e435e..02fe8edf271 100644
--- a/test/lisp/net/tramp-archive-tests.el
+++ b/test/lisp/net/tramp-archive-tests.el
@@ -157,89 +157,93 @@ variables, so we check the Emacs version directly."
   "Check archive file name components."
   (skip-unless tramp-archive-enabled)
 
-  (with-parsed-tramp-archive-file-name tramp-archive-test-archive nil
-    (should (string-equal method tramp-archive-method))
-    (should-not user)
-    (should-not domain)
-    (should
-     (string-equal
-      host
-      (file-remote-p
-       (tramp-archive-gvfs-file-name tramp-archive-test-archive) 'host)))
-    (should
-     (string-equal
-      host
-      (url-hexify-string (concat "file://" tramp-archive-test-file-archive))))
-    (should-not port)
-    (should (string-equal localname "/"))
-    (should (string-equal archive tramp-archive-test-file-archive)))
-
-  ;; Localname.
-  (with-parsed-tramp-archive-file-name
-      (concat tramp-archive-test-archive "foo") nil
-    (should (string-equal method tramp-archive-method))
-    (should-not user)
-    (should-not domain)
-    (should
-     (string-equal
-      host
-      (file-remote-p
-       (tramp-archive-gvfs-file-name tramp-archive-test-archive) 'host)))
-   (should
-     (string-equal
-      host
-      (url-hexify-string (concat "file://" tramp-archive-test-file-archive))))
-    (should-not port)
-    (should (string-equal localname "/foo"))
-    (should (string-equal archive tramp-archive-test-file-archive)))
-
-  ;; File archive in file archive.
-  (let* ((tramp-archive-test-file-archive
-          (concat tramp-archive-test-archive "baz.tar"))
-         (tramp-archive-test-archive
-          (file-name-as-directory tramp-archive-test-file-archive))
-         (tramp-methods (cons `(,tramp-archive-method) tramp-methods))
-         (tramp-gvfs-methods tramp-archive-all-gvfs-methods))
-    (unwind-protect
-        (with-parsed-tramp-archive-file-name
-            (expand-file-name "bar" tramp-archive-test-archive) nil
-          (should (string-equal method tramp-archive-method))
-          (should-not user)
-          (should-not domain)
-          (should
-           (string-equal
-            host
-            (file-remote-p
-             (tramp-archive-gvfs-file-name tramp-archive-test-archive) 'host)))
-          ;; We reimplement the logic of tramp-archive.el here.  Don't
-          ;; know, whether it is worth the test.
-          (should
-           (string-equal
-            host
-            (url-hexify-string
-             (concat
-              (tramp-gvfs-url-file-name
-               (tramp-make-tramp-file-name
-                tramp-archive-method
-                ;; User and Domain.
-                nil nil
-                ;; Host.
-                (url-hexify-string
-                 (concat
-                  "file://"
-                  ;; `directory-file-name' does not leave file archive
-                  ;; boundaries.  So we must cut the trailing slash
-                  ;; ourselves.
-                  (substring
-                   (file-name-directory tramp-archive-test-file-archive) 0 -1)))
-                nil "/"))
-              (file-name-nondirectory tramp-archive-test-file-archive)))))
-          (should-not port)
-          (should (string-equal localname "/bar"))
-          (should (string-equal archive tramp-archive-test-file-archive)))
+  ;; Suppress method name check.
+  (let ((non-essential t))
+    (with-parsed-tramp-archive-file-name tramp-archive-test-archive nil
+      (should (string-equal method tramp-archive-method))
+      (should-not user)
+      (should-not domain)
+      (should
+       (string-equal
+        host
+        (file-remote-p
+         (tramp-archive-gvfs-file-name tramp-archive-test-archive) 'host)))
+      (should
+       (string-equal
+        host
+        (url-hexify-string (concat "file://" tramp-archive-test-file-archive))))
+      (should-not port)
+      (should (string-equal localname "/"))
+      (should (string-equal archive tramp-archive-test-file-archive)))
+
+    ;; Localname.
+    (with-parsed-tramp-archive-file-name
+        (concat tramp-archive-test-archive "foo") nil
+      (should (string-equal method tramp-archive-method))
+      (should-not user)
+      (should-not domain)
+      (should
+       (string-equal
+        host
+        (file-remote-p
+         (tramp-archive-gvfs-file-name tramp-archive-test-archive) 'host)))
+      (should
+       (string-equal
+        host
+        (url-hexify-string (concat "file://" tramp-archive-test-file-archive))))
+      (should-not port)
+      (should (string-equal localname "/foo"))
+      (should (string-equal archive tramp-archive-test-file-archive)))
+
+    ;; File archive in file archive.
+    (let* ((tramp-archive-test-file-archive
+            (concat tramp-archive-test-archive "baz.tar"))
+           (tramp-archive-test-archive
+            (file-name-as-directory tramp-archive-test-file-archive))
+           (tramp-methods (cons `(,tramp-archive-method) tramp-methods))
+           (tramp-gvfs-methods tramp-archive-all-gvfs-methods))
+      (unwind-protect
+          (with-parsed-tramp-archive-file-name
+              (expand-file-name "bar" tramp-archive-test-archive) nil
+            (should (string-equal method tramp-archive-method))
+            (should-not user)
+            (should-not domain)
+            (should
+             (string-equal
+              host
+              (file-remote-p
+               (tramp-archive-gvfs-file-name tramp-archive-test-archive)
+               'host)))
+            ;; We reimplement the logic of tramp-archive.el here.
+            ;; Don't know, whether it is worth the test.
+            (should
+             (string-equal
+              host
+              (url-hexify-string
+               (concat
+                (tramp-gvfs-url-file-name
+                 (tramp-make-tramp-file-name
+                  tramp-archive-method
+                  ;; User and Domain.
+                  nil nil
+                  ;; Host.
+                  (url-hexify-string
+                   (concat
+                    "file://"
+                    ;; `directory-file-name' does not leave file
+                    ;; archive boundaries.  So we must cut the
+                    ;; trailing slash ourselves.
+                    (substring
+                     (file-name-directory tramp-archive-test-file-archive)
+                     0 -1)))
+                  nil "/"))
+                (file-name-nondirectory tramp-archive-test-file-archive)))))
+            (should-not port)
+            (should (string-equal localname "/bar"))
+            (should (string-equal archive tramp-archive-test-file-archive)))
 
-      ;; Cleanup.
-      (tramp-archive-cleanup-hash))))
+        ;; Cleanup.
+        (tramp-archive-cleanup-hash)))))
 
 (ert-deftest tramp-archive-test05-expand-file-name ()
   "Check `expand-file-name'."
diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index 5fc37c1934f..38f9af230a3 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -176,10 +176,9 @@ properly.  BODY shall not contain a timeout."
          (let ((tramp--test-instrument-test-case-p t)) ,@body)
        ;; Unwind forms.
        (when (and (null tramp--test-instrument-test-case-p) (> tramp-verbose 3))
-         (with-parsed-tramp-file-name tramp-test-temporary-file-directory nil
-           (with-current-buffer (tramp-get-connection-buffer v)
-             (message "%s" (buffer-string)))
-           (with-current-buffer (tramp-get-debug-buffer v)
+         (dolist (buf (tramp-list-tramp-buffers))
+           (message ";; %s" buf)
+           (with-current-buffer buf
              (message "%s" (buffer-string))))))))
 
 (defsubst tramp--test-message (fmt-string &rest arguments)
@@ -412,15 +411,26 @@ properly.  BODY shall not contain a timeout."
 
 (ert-deftest tramp-test02-file-name-dissect ()
   "Check remote file name components."
+  ;; `user-error' has appeared in Emacs 24.3.
+  (skip-unless (fboundp 'user-error))
+
   (let ((tramp-default-method "default-method")
         (tramp-default-user "default-user")
         (tramp-default-host "default-host")
         tramp-default-method-alist
         tramp-default-user-alist
         tramp-default-host-alist
+        ;; Suppress method name check.
+        (non-essential t)
         ;; Suppress check for multihops.
         (tramp-cache-data (make-hash-table :test #'equal))
         (tramp-connection-properties '((nil "login-program" t))))
+    ;; An unknown method shall raise an error.
+    (let (non-essential)
+      (should-error
+       (expand-file-name "/method:user@host:")
+       :type 'user-error))
+
     ;; Expand `tramp-default-user' and `tramp-default-host'.
     (should (string-equal
              (file-remote-p "/method::")
@@ -527,7 +537,8 @@ properly.  BODY shall not contain a timeout."
     (should (string-equal
              (file-remote-p "/-:user@host#1234:" 'method) "default-method"))
     (should (string-equal (file-remote-p "/-:user@host#1234:" 'user) "user"))
-    (should (string-equal (file-remote-p "/-:user@host#1234:" 'host) "host#1234"))
+    (should (string-equal
+             (file-remote-p "/-:user@host#1234:" 'host) "host#1234"))
     (should (string-equal (file-remote-p "/-:user@host#1234:" 'localname) ""))
     (should (string-equal (file-remote-p "/-:user@host#1234:" 'hop) nil))
 
@@ -563,7 +574,8 @@ properly.  BODY shall not contain a timeout."
     (should (string-equal
              (file-remote-p "/-:1.2.3.4:")
              (format "/%s:%s@%s:" "default-method" "default-user" "1.2.3.4")))
-    (should (string-equal (file-remote-p "/-:1.2.3.4:" 'method) "default-method"))
+    (should (string-equal
+             (file-remote-p "/-:1.2.3.4:" 'method) "default-method"))
     (should (string-equal (file-remote-p "/-:1.2.3.4:" 'user) "default-user"))
     (should (string-equal (file-remote-p "/-:1.2.3.4:" 'host) "1.2.3.4"))
     (should (string-equal (file-remote-p "/-:1.2.3.4:" 'localname) ""))
@@ -852,11 +864,16 @@ properly.  BODY shall not contain a timeout."
 (ert-deftest tramp-test02-file-name-dissect-simplified ()
   "Check simplified file name components."
   :tags '(:expensive-test)
+  ;; `user-error' has appeared in Emacs 24.3.
+  (skip-unless (fboundp 'user-error))
+
   (let ((tramp-default-method "default-method")
         (tramp-default-user "default-user")
         (tramp-default-host "default-host")
         tramp-default-user-alist
         tramp-default-host-alist
+        ;; Suppress method name check.
+        (non-essential t)
         ;; Suppress check for multihops.
         (tramp-cache-data (make-hash-table :test #'equal))
         (tramp-connection-properties '((nil "login-program" t)))
@@ -864,6 +881,12 @@ properly.  BODY shall not contain a timeout."
     (unwind-protect
         (progn
           (tramp-change-syntax 'simplified)
+          ;; An unknown default method shall raise an error.
+          (let (non-essential)
+            (should-error
+             (expand-file-name "/user@host:")
+             :type 'user-error))
+
           ;; Expand `tramp-default-method' and `tramp-default-user'.
           (should (string-equal
                    (file-remote-p "/host:")
@@ -1175,12 +1198,17 @@ properly.  BODY shall not contain a timeout."
 (ert-deftest tramp-test02-file-name-dissect-separate ()
   "Check separate file name components."
   :tags '(:expensive-test)
+  ;; `user-error' has appeared in Emacs 24.3.
+  (skip-unless (fboundp 'user-error))
+
   (let ((tramp-default-method "default-method")
         (tramp-default-user "default-user")
         (tramp-default-host "default-host")
         tramp-default-method-alist
         tramp-default-user-alist
         tramp-default-host-alist
+        ;; Suppress method name check.
+        (non-essential t)
         ;; Suppress check for multihops.
         (tramp-cache-data (make-hash-table :test #'equal))
         (tramp-connection-properties '((nil "login-program" t)))
@@ -1188,6 +1216,12 @@ properly.  BODY shall not contain a timeout."
     (unwind-protect
         (progn
           (tramp-change-syntax 'separate)
+          ;; An unknown method shall raise an error.
+          (let (non-essential)
+            (should-error
+             (expand-file-name "/[method/user@host]")
+             :type 'user-error))
+
           ;; Expand `tramp-default-user' and `tramp-default-host'.
           (should (string-equal
                    (file-remote-p "/[method/]")
@@ -1826,24 +1860,30 @@ properly.  BODY shall not contain a timeout."
 (ert-deftest tramp-test03-file-name-defaults ()
   "Check default values for some methods."
   ;; Default values in tramp-adb.el.
-  (should (string-equal (file-remote-p "/adb::" 'host) ""))
+  (when (assoc "adb" tramp-methods)
+    (should (string-equal (file-remote-p "/adb::" 'host) "")))
   ;; Default values in tramp-ftp.el.
-  (should (string-equal (file-remote-p "/-:ftp.host:" 'method) "ftp"))
-  (dolist (u '("ftp" "anonymous"))
-    (should (string-equal (file-remote-p (format "/-:%s@:" u) 'method) "ftp")))
+  (when (assoc "ftp" tramp-methods)
+    (should (string-equal (file-remote-p "/-:ftp.host:" 'method) "ftp"))
+    (dolist (u '("ftp" "anonymous"))
+      (should
+       (string-equal (file-remote-p (format "/-:%s@:" u) 'method) "ftp"))))
   ;; Default values in tramp-sh.el and tramp-sudoedit.el.
-  (dolist (h `("127.0.0.1" "[::1]" "localhost" "localhost6" ,(system-name)))
-    (should
-     (string-equal (file-remote-p (format "/-:root@%s:" h) 'method) "su")))
-  (dolist (m '("su" "sudo" "ksu" "doas" "sudoedit"))
-    (should (string-equal (file-remote-p (format "/%s::" m) 'user) "root"))
-    (should
-     (string-equal (file-remote-p (format "/%s::" m) 'host) (system-name))))
-  (dolist (m '("rcp" "remcp" "rsh" "telnet" "krlogin" "fcp" "nc"))
-    (should
-     (string-equal (file-remote-p (format "/%s::" m) 'user) (user-login-name))))
+  (when (assoc "su" tramp-methods)
+    (dolist (h `("127.0.0.1" "[::1]" "localhost" "localhost6" ,(system-name)))
+      (should
+       (string-equal (file-remote-p (format "/-:root@%s:" h) 'method) "su")))
+    (dolist (m '("su" "sudo" "ksu" "doas" "sudoedit"))
+      (should (string-equal (file-remote-p (format "/%s::" m) 'user) "root"))
+      (should
+       (string-equal (file-remote-p (format "/%s::" m) 'host) (system-name))))
+    (dolist (m '("rcp" "remcp" "rsh" "telnet" "krlogin" "fcp" "nc"))
+      (should
+       (string-equal
+        (file-remote-p (format "/%s::" m) 'user) (user-login-name)))))
   ;; Default values in tramp-smb.el.
-  (should (string-equal (file-remote-p "/smb::" 'user) nil)))
+  (when (assoc "smb" tramp-methods)
+    (should (string-equal (file-remote-p "/smb::" 'user) nil))))
 
 ;; The following test is inspired by Bug#30946.
 (ert-deftest tramp-test03-file-name-host-rules ()
@@ -1898,121 +1938,129 @@ properly.  BODY shall not contain a timeout."
 
 (ert-deftest tramp-test04-substitute-in-file-name ()
   "Check `substitute-in-file-name'."
-  (should (string-equal (substitute-in-file-name "/method:host:///foo") "/foo"))
-  (should
-   (string-equal
-    (substitute-in-file-name "/method:host://foo") "/method:host:/foo"))
-  (should
-   (string-equal (substitute-in-file-name "/method:host:/path///foo") "/foo"))
-  (should
-   (string-equal
-    (substitute-in-file-name "/method:host:/path//foo") "/method:host:/foo"))
-  ;; Quoting local part.
-  (should
-   (string-equal
-    (substitute-in-file-name "/method:host:/:///foo") "/method:host:/:///foo"))
-  (should
-   (string-equal
-    (substitute-in-file-name "/method:host:/://foo") "/method:host:/://foo"))
-  (should
-   (string-equal
-    (substitute-in-file-name "/method:host:/:/path///foo")
-    "/method:host:/:/path///foo"))
-  (should
-   (string-equal
-    (substitute-in-file-name "/method:host:/:/path//foo")
-    "/method:host:/:/path//foo"))
-
-  (should
-   (string-equal (substitute-in-file-name "/method:host://~foo") "/~foo"))
-  (should
-   (string-equal
-    (substitute-in-file-name "/method:host:/~foo") "/method:host:/~foo"))
-  (should
-   (string-equal (substitute-in-file-name "/method:host:/path//~foo") "/~foo"))
-  ;; (substitute-in-file-name "/path/~foo") expands only for a local
-  ;; user "foo" to "/~foo"".  Otherwise, it doesn't expand.
-  (should
-   (string-equal
-    (substitute-in-file-name
-     "/method:host:/path/~foo") "/method:host:/path/~foo"))
-  ;; Quoting local part.
-  (should
-   (string-equal
-    (substitute-in-file-name "/method:host:/://~foo") "/method:host:/://~foo"))
-  (should
-   (string-equal
-    (substitute-in-file-name "/method:host:/:/~foo") "/method:host:/:/~foo"))
-  (should
-   (string-equal
-    (substitute-in-file-name
-     "/method:host:/:/path//~foo") "/method:host:/:/path//~foo"))
-  (should
-   (string-equal
-    (substitute-in-file-name
-     "/method:host:/:/path/~foo") "/method:host:/:/path/~foo"))
+  ;; Suppress method name check.
+  (let ((tramp-methods (cons '("method") tramp-methods)))
+    (should
+     (string-equal (substitute-in-file-name "/method:host:///foo") "/foo"))
+    (should
+     (string-equal
+      (substitute-in-file-name "/method:host://foo") "/method:host:/foo"))
+    (should
+     (string-equal (substitute-in-file-name "/method:host:/path///foo") "/foo"))
+    (should
+     (string-equal
+      (substitute-in-file-name "/method:host:/path//foo") "/method:host:/foo"))
+    ;; Quoting local part.
+    (should
+     (string-equal
+      (substitute-in-file-name "/method:host:/:///foo")
+      "/method:host:/:///foo"))
+    (should
+     (string-equal
+      (substitute-in-file-name "/method:host:/://foo") "/method:host:/://foo"))
+    (should
+     (string-equal
+      (substitute-in-file-name "/method:host:/:/path///foo")
+      "/method:host:/:/path///foo"))
+    (should
+     (string-equal
+      (substitute-in-file-name "/method:host:/:/path//foo")
+      "/method:host:/:/path//foo"))
 
-  (let (process-environment)
+    (should
+     (string-equal (substitute-in-file-name "/method:host://~foo") "/~foo"))
     (should
      (string-equal
-      (substitute-in-file-name "/method:host:/path/$FOO")
-      "/method:host:/path/$FOO"))
-    (setenv "FOO" "bla")
+      (substitute-in-file-name "/method:host:/~foo") "/method:host:/~foo"))
     (should
      (string-equal
-      (substitute-in-file-name "/method:host:/path/$FOO")
-      "/method:host:/path/bla"))
+      (substitute-in-file-name "/method:host:/path//~foo") "/~foo"))
+    ;; (substitute-in-file-name "/path/~foo") expands only for a local
+    ;; user "foo" to "/~foo"".  Otherwise, it doesn't expand.
     (should
      (string-equal
-      (substitute-in-file-name "/method:host:/path/$$FOO")
-      "/method:host:/path/$FOO"))
+      (substitute-in-file-name
+       "/method:host:/path/~foo") "/method:host:/path/~foo"))
     ;; Quoting local part.
     (should
      (string-equal
-      (substitute-in-file-name "/method:host:/:/path/$FOO")
-      "/method:host:/:/path/$FOO"))
-    (setenv "FOO" "bla")
+      (substitute-in-file-name "/method:host:/://~foo")
+      "/method:host:/://~foo"))
     (should
      (string-equal
-      (substitute-in-file-name "/method:host:/:/path/$FOO")
-      "/method:host:/:/path/$FOO"))
+      (substitute-in-file-name "/method:host:/:/~foo") "/method:host:/:/~foo"))
     (should
      (string-equal
-      (substitute-in-file-name "/method:host:/:/path/$$FOO")
-      "/method:host:/:/path/$$FOO"))))
+      (substitute-in-file-name
+       "/method:host:/:/path//~foo") "/method:host:/:/path//~foo"))
+    (should
+     (string-equal
+      (substitute-in-file-name
+       "/method:host:/:/path/~foo") "/method:host:/:/path/~foo"))
+
+    (let (process-environment)
+      (should
+       (string-equal
+        (substitute-in-file-name "/method:host:/path/$FOO")
+        "/method:host:/path/$FOO"))
+      (setenv "FOO" "bla")
+      (should
+       (string-equal
+        (substitute-in-file-name "/method:host:/path/$FOO")
+        "/method:host:/path/bla"))
+      (should
+       (string-equal
+        (substitute-in-file-name "/method:host:/path/$$FOO")
+        "/method:host:/path/$FOO"))
+      ;; Quoting local part.
+      (should
+       (string-equal
+        (substitute-in-file-name "/method:host:/:/path/$FOO")
+        "/method:host:/:/path/$FOO"))
+      (setenv "FOO" "bla")
+      (should
+       (string-equal
+        (substitute-in-file-name "/method:host:/:/path/$FOO")
+        "/method:host:/:/path/$FOO"))
+      (should
+       (string-equal
+        (substitute-in-file-name "/method:host:/:/path/$$FOO")
+        "/method:host:/:/path/$$FOO")))))
 
 (ert-deftest tramp-test05-expand-file-name ()
   "Check `expand-file-name'."
-  (should
-   (string-equal
-    (expand-file-name "/method:host:/path/./file") "/method:host:/path/file"))
-  (should
-   (string-equal
-    (expand-file-name "/method:host:/path/../file") "/method:host:/file"))
-  (should
-   (string-equal
-    (expand-file-name "/method:host:/path/.") "/method:host:/path"))
-  (should
-   (string-equal
-    (expand-file-name "/method:host:/path/..") "/method:host:/"))
-  (should
-   (string-equal
-    (expand-file-name "." "/method:host:/path/") "/method:host:/path"))
-  (should
-   (string-equal
-    (expand-file-name "" "/method:host:/path/") "/method:host:/path"))
-  ;; Quoting local part.
-  (should
-   (string-equal
-    (expand-file-name "/method:host:/:/path/./file")
-    "/method:host:/:/path/file"))
-  (should
-   (string-equal
-    (expand-file-name "/method:host:/:/path/../file") "/method:host:/:/file"))
-  (should
-   (string-equal
-    (expand-file-name "/method:host:/:/~/path/./file")
-    "/method:host:/:/~/path/file")))
+  ;; Suppress method name check.
+  (let ((tramp-methods (cons '("method") tramp-methods)))
+    (should
+     (string-equal
+      (expand-file-name "/method:host:/path/./file") "/method:host:/path/file"))
+    (should
+     (string-equal
+      (expand-file-name "/method:host:/path/../file") "/method:host:/file"))
+    (should
+     (string-equal
+      (expand-file-name "/method:host:/path/.") "/method:host:/path"))
+    (should
+     (string-equal
+      (expand-file-name "/method:host:/path/..") "/method:host:/"))
+    (should
+     (string-equal
+      (expand-file-name "." "/method:host:/path/") "/method:host:/path"))
+    (should
+     (string-equal
+      (expand-file-name "" "/method:host:/path/") "/method:host:/path"))
+    ;; Quoting local part.
+    (should
+     (string-equal
+      (expand-file-name "/method:host:/:/path/./file")
+      "/method:host:/:/path/file"))
+    (should
+     (string-equal
+      (expand-file-name "/method:host:/:/path/../file") "/method:host:/:/file"))
+    (should
+     (string-equal
+      (expand-file-name "/method:host:/:/~/path/./file")
+      "/method:host:/:/~/path/file"))))
 
 ;; The following test is inspired by Bug#26911 and Bug#34834.  They
 ;; are rather bugs in `expand-file-name', and it fails for all Emacs
@@ -2042,48 +2090,51 @@ properly.  BODY shall not contain a timeout."
   "Check `directory-file-name'.
 This checks also `file-name-as-directory', `file-name-directory',
 `file-name-nondirectory' and `unhandled-file-name-directory'."
-  (should
-   (string-equal
-    (directory-file-name "/method:host:/path/to/file")
-    "/method:host:/path/to/file"))
-  (should
-   (string-equal
-    (directory-file-name "/method:host:/path/to/file/")
-    "/method:host:/path/to/file"))
-  (should
-   (string-equal
-    (directory-file-name "/method:host:/path/to/file//")
-    "/method:host:/path/to/file"))
-  (should
-   (string-equal
-    (file-name-as-directory "/method:host:/path/to/file")
-    "/method:host:/path/to/file/"))
-  (should
-   (string-equal
-    (file-name-as-directory "/method:host:/path/to/file/")
-    "/method:host:/path/to/file/"))
-  (should
-   (string-equal
-    (file-name-directory "/method:host:/path/to/file")
-    "/method:host:/path/to/"))
-  (should
-   (string-equal
-    (file-name-directory "/method:host:/path/to/file/")
-    "/method:host:/path/to/file/"))
-  (should
-   (string-equal (file-name-directory "/method:host:file") "/method:host:"))
-  (should
-   (string-equal
-    (file-name-directory "/method:host:path/") "/method:host:path/"))
-  (should
-   (string-equal
-    (file-name-directory "/method:host:path/to") "/method:host:path/"))
-  (should
-   (string-equal (file-name-nondirectory "/method:host:/path/to/file") "file"))
-  (should
-   (string-equal (file-name-nondirectory "/method:host:/path/to/file/") ""))
-  (should-not
-   (unhandled-file-name-directory "/method:host:/path/to/file"))
+  ;; Suppress method name check.
+  (let ((tramp-methods (cons '("method") tramp-methods)))
+    (should
+     (string-equal
+      (directory-file-name "/method:host:/path/to/file")
+      "/method:host:/path/to/file"))
+    (should
+     (string-equal
+      (directory-file-name "/method:host:/path/to/file/")
+      "/method:host:/path/to/file"))
+    (should
+     (string-equal
+      (directory-file-name "/method:host:/path/to/file//")
+      "/method:host:/path/to/file"))
+    (should
+     (string-equal
+      (file-name-as-directory "/method:host:/path/to/file")
+      "/method:host:/path/to/file/"))
+    (should
+     (string-equal
+      (file-name-as-directory "/method:host:/path/to/file/")
+      "/method:host:/path/to/file/"))
+    (should
+     (string-equal
+      (file-name-directory "/method:host:/path/to/file")
+      "/method:host:/path/to/"))
+    (should
+     (string-equal
+      (file-name-directory "/method:host:/path/to/file/")
+      "/method:host:/path/to/file/"))
+    (should
+     (string-equal (file-name-directory "/method:host:file") "/method:host:"))
+    (should
+     (string-equal
+      (file-name-directory "/method:host:path/") "/method:host:path/"))
+    (should
+     (string-equal
+      (file-name-directory "/method:host:path/to") "/method:host:path/"))
+    (should
+     (string-equal
+      (file-name-nondirectory "/method:host:/path/to/file") "file"))
+    (should
+     (string-equal (file-name-nondirectory "/method:host:/path/to/file/") ""))
+    (should-not
+     (unhandled-file-name-directory "/method:host:/path/to/file")))
 
   ;; Bug#10085.
   (when (tramp--test-enabled) ;; Packages like tramp-gvfs.el might be disabled.
@@ -3968,7 +4019,6 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   ;; name handlers since Emacs 27.
   (skip-unless (tramp--test-emacs27-p))
 
-  (tramp--test-instrument-test-case 0
   (dolist (quoted (if (tramp--test-expensive-test) '(nil t) '(nil)))
     (let ((default-directory tramp-test-temporary-file-directory)
           (tmp-name (tramp--test-make-temp-name nil quoted))
@@ -4097,7 +4147,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
 
             ;; Cleanup.
             (ignore-errors (delete-process proc))
-            (ignore-errors (kill-buffer stderr)))))))))
+            (ignore-errors (kill-buffer stderr))))))))
 
 (ert-deftest tramp-test31-interrupt-process ()
   "Check `interrupt-process'."
@@ -4107,7 +4157,10 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   ;; Since Emacs 26.1.
   (skip-unless (boundp 'interrupt-process-functions))
 
-  (let ((default-directory tramp-test-temporary-file-directory)
+  ;; We must use `file-truename' for the temporary directory, in
+  ;; order to establish the connection prior running an asynchronous
+  ;; process.
+  (let ((default-directory (file-truename tramp-test-temporary-file-directory))
         kill-buffer-query-functions proc)
     (unwind-protect
         (with-temp-buffer
@@ -4602,7 +4655,11 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   (skip-unless (tramp--test-sh-p))
 
   (dolist (quoted (if (tramp--test-expensive-test) '(nil t) '(nil)))
-    (let* ((default-directory tramp-test-temporary-file-directory)
+    ;; We must use `file-truename' for the temporary directory, in
+    ;; order to establish the connection prior running an asynchronous
+    ;; process.
+    (let* ((default-directory
+             (file-truename tramp-test-temporary-file-directory))
            (tmp-name1 (tramp--test-make-temp-name nil quoted))
            (tmp-name2 (expand-file-name "foo" tmp-name1))
            (tramp-remote-process-environment tramp-remote-process-environment)
@@ -5625,7 +5682,9 @@ process sentinels.  They shall not disturb each other."
   (let ((default-directory (expand-file-name temporary-file-directory))
         (code
          (format
-          "(message \"Tramp loaded: %%s\" (and (file-remote-p %S) t))"
+          ;; Suppress method name check.
+          "(let ((non-essential t)) \
+             (message \"Tramp loaded: %%s\" (and (file-remote-p %S) t)))"
           tramp-test-temporary-file-directory)))
     (should
      (string-match
@@ -5804,9 +5863,9 @@ Since it unloads Tramp, it shall be the last test to run."
 ;;   do not work properly for `nextcloud'.
 ;; * Fix `tramp-test29-start-file-process' and
 ;;   `tramp-test30-make-process' on MS Windows (`process-send-eof'?).
+;; * Implement `tramp-test31-interrupt-process' for `adb'.
 ;; * Fix Bug#16928 in `tramp-test43-asynchronous-requests'.  Looks
 ;;   like it is resolved now.  Remove `:unstable' tag?
-;; * Implement `tramp-test31-interrupt-process' for `adb'.
 
 (provide 'tramp-tests)
 ;;; tramp-tests.el ends here