Adapt Tramp tests

* test/lisp/net/tramp-archive-tests.el (ert-resource-directory-format)
(ert-resource-directory-trim-left-regexp)
(ert-resource-directory-trim-right-regexp, ert-resource-directory)
(ert-resource-file): Don't define.
(tramp-archive--test-emacs28-p): Remove.
(top): Remove unneeded skips.  Use original objects instead of
their `tramp-compat-' counterparts when possible.

* test/lisp/net/tramp-tests.el (seq): Don't require.
(lock-file-name-transforms, process-file-return-signal-string)
(remote-file-name-inhibit-locks, dired-copy-dereference): Don't declare.
(ert-resource-directory-format)
(ert-resource-directory-trim-left-regexp)
(ert-resource-directory-trim-right-regexp, ert-resource-directory)
(ert-resource-file): Don't define.
(tramp--test-emacs28-p): Remove.
(top): Remove unneeded skips.  Use original objects instead of
their `tramp-compat-' counterparts when possible.

2 files changed, 127 insertions, 278 deletions

diff --git a/test/lisp/net/tramp-archive-tests.el b/test/lisp/net/tramp-archive-tests.el
index 1ca2fa9b9b3..94bb245ee4a 100644
--- a/test/lisp/net/tramp-archive-tests.el
+++ b/test/lisp/net/tramp-archive-tests.el
@@ -33,50 +33,6 @@
 (require 'tramp-archive)
 (defvar tramp-persistency-file-name)
 
-;; `ert-resource-file' was introduced in Emacs 28.1.
-(unless (macrop 'ert-resource-file)
-  (eval-and-compile
-    (defvar ert-resource-directory-format "%s-resources/"
-      "Format for `ert-resource-directory'.")
-    (defvar ert-resource-directory-trim-left-regexp ""
-      "Regexp for `string-trim' (left) used by `ert-resource-directory'.")
-    (defvar ert-resource-directory-trim-right-regexp
-      (rx (? "-test" (? "s")) ".el")
-      "Regexp for `string-trim' (right) used by `ert-resource-directory'.")
-
-    (defmacro ert-resource-directory ()
-      "Return absolute file name of the resource directory for this file.
-
-The path to the resource directory is the \"resources\" directory
-in the same directory as the test file.
-
-If that directory doesn't exist, use the directory named like the
-test file but formatted by `ert-resource-directory-format' and trimmed
-using `string-trim' with arguments
-`ert-resource-directory-trim-left-regexp' and
-`ert-resource-directory-trim-right-regexp'.  The default values mean
-that if called from a test file named \"foo-tests.el\", return
-the absolute file name for \"foo-resources\"."
-      `(let* ((testfile ,(or (bound-and-true-p byte-compile-current-file)
-                             (and load-in-progress load-file-name)
-                             buffer-file-name))
-              (default-directory (file-name-directory testfile)))
-         (file-truename
-          (if (file-accessible-directory-p "resources/")
-              (expand-file-name "resources/")
-            (expand-file-name
-             (format
-              ert-resource-directory-format
-              (string-trim testfile
-                           ert-resource-directory-trim-left-regexp
-                           ert-resource-directory-trim-right-regexp)))))))
-
-    (defmacro ert-resource-file (file)
-      "Return file name of resource file named FILE.
-A resource file is in the resource directory as per
-`ert-resource-directory'."
-      `(expand-file-name ,file (ert-resource-directory)))))
-
 (defvar tramp-archive-test-file-archive (ert-resource-file "foo.tar.gz")
   "The test file archive.")
 
@@ -121,12 +77,6 @@ the origin of the temporary TMPFILE, have no write permissions."
      (directory-files tmpfile 'full directory-files-no-dot-files-regexp))
     (delete-directory tmpfile)))
 
-(defun tramp-archive--test-emacs28-p ()
-  "Check for Emacs version >= 28.1.
-Some semantics has been changed for there, without new functions or
-variables, so we check the Emacs version directly."
-  (>= emacs-major-version 28))
-
 (ert-deftest tramp-archive-test00-availability ()
   "Test availability of archive file name functions."
   :expected-result (if tramp-archive-enabled :passed :failed)
@@ -881,7 +831,7 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
   (let ((fsi (file-system-info tramp-archive-test-archive)))
     (skip-unless fsi)
     (should (and (consp fsi)
-                 (tramp-compat-length= fsi 3)
+                 (length= fsi 3)
                  (numberp (nth 0 fsi))
                  ;; FREE and AVAIL are always 0.
                  (zerop (nth 1 fsi))
@@ -925,13 +875,7 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
       (dolist (default-directory
                 (append
                  `(,temporary-file-directory)
-                 ;;  Starting Emacs in a directory which has
-                 ;; `tramp-archive-file-name-regexp' syntax is
-                 ;; supported only with Emacs > 27.2 (sigh!).
-                 ;; (Bug#48476)
-                 (and (tramp-archive--test-emacs28-p)
-                      `(,(file-name-as-directory
-                          tramp-archive-test-directory)))))
+                 `(,(file-name-as-directory tramp-archive-test-directory))))
         (dolist (file `("/mock::foo" ,(concat tramp-archive-test-archive "foo")))
           (should
            (string-match
diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index e958cd354bc..7673ee88569 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -46,7 +46,6 @@
 (require 'dired-aux)
 (require 'tramp)
 (require 'ert-x)
-(require 'seq) ; For `seq-random-elt', autoloaded since Emacs 28.1
 (require 'tar-mode)
 (require 'trace)
 (require 'vc)
@@ -75,60 +74,10 @@
 (defvar tramp-remote-process-environment)
 (defvar tramp-use-connection-share)
 
-;; Needed for Emacs 27.
-(defvar lock-file-name-transforms)
-(defvar process-file-return-signal-string)
-(defvar remote-file-name-inhibit-locks)
-(defvar dired-copy-dereference)
-
 ;; Declared in Emacs 30.
 (defvar remote-file-name-access-timeout)
 (defvar remote-file-name-inhibit-delete-by-moving-to-trash)
 
-;; `ert-resource-file' was introduced in Emacs 28.1.
-(unless (macrop 'ert-resource-file)
-  (eval-and-compile
-    (defvar ert-resource-directory-format "%s-resources/"
-      "Format for `ert-resource-directory'.")
-    (defvar ert-resource-directory-trim-left-regexp ""
-      "Regexp for `string-trim' (left) used by `ert-resource-directory'.")
-    (defvar ert-resource-directory-trim-right-regexp
-      (rx (? "-test" (? "s")) ".el")
-      "Regexp for `string-trim' (right) used by `ert-resource-directory'.")
-
-    (defmacro ert-resource-directory ()
-      "Return absolute file name of the resource directory for this file.
-
-The path to the resource directory is the \"resources\" directory
-in the same directory as the test file.
-
-If that directory doesn't exist, use the directory named like the
-test file but formatted by `ert-resource-directory-format' and trimmed
-using `string-trim' with arguments
-`ert-resource-directory-trim-left-regexp' and
-`ert-resource-directory-trim-right-regexp'.  The default values mean
-that if called from a test file named \"foo-tests.el\", return
-the absolute file name for \"foo-resources\"."
-      `(let* ((testfile ,(or (bound-and-true-p byte-compile-current-file)
-                             (and load-in-progress load-file-name)
-                             buffer-file-name))
-              (default-directory (file-name-directory testfile)))
-         (file-truename
-          (if (file-accessible-directory-p "resources/")
-              (expand-file-name "resources/")
-            (expand-file-name
-             (format
-              ert-resource-directory-format
-              (string-trim testfile
-                           ert-resource-directory-trim-left-regexp
-                           ert-resource-directory-trim-right-regexp)))))))
-
-    (defmacro ert-resource-file (file)
-      "Return file name of resource file named FILE.
-A resource file is in the resource directory as per
-`ert-resource-directory'."
-      `(expand-file-name ,file (ert-resource-directory)))))
-
 ;; `ert-remote-temporary-file-directory' was introduced in Emacs 29.1.
 ;; Adapting `tramp-remote-path' happens also there.
 (unless (boundp 'ert-remote-temporary-file-directory)
@@ -2350,8 +2299,6 @@ is greater than 10.
   (skip-unless (tramp--test-enabled))
   ;; Methods with a share do not expand "/path/..".
   (skip-unless (not (tramp--test-share-p)))
-  ;; The bugs are fixed in Emacs 28.1.
-  (skip-unless (tramp--test-emacs28-p))
 
   (should
    (string-equal
@@ -2646,18 +2593,15 @@ This checks also `file-name-as-directory', `file-name-directory',
               (should (string-equal (buffer-string) "foo"))
               (should (= point (point))))
             ;; Insert another string.
-            ;; `replace-string-in-region' was introduced in Emacs 28.1.
-            (when (tramp--test-emacs28-p)
-              (let ((point (point)))
-                (with-no-warnings
-                  (replace-string-in-region "foo" "bar" (point-min) (point-max)))
-                (goto-char point)
-                (should
-                 (equal
-                  (insert-file-contents tmp-name nil nil nil 'replace)
-                  `(,(expand-file-name tmp-name) 3)))
-                (should (string-equal (buffer-string) "foo"))
-                (should (= point (point)))))
+            (let ((point (point)))
+              (replace-string-in-region "foo" "bar" (point-min) (point-max))
+              (goto-char point)
+              (should
+               (equal
+                (insert-file-contents tmp-name nil nil nil 'replace)
+                `(,(expand-file-name tmp-name) 3)))
+              (should (string-equal (buffer-string) "foo"))
+              (should (= point (point))))
             ;; Error case.
             (delete-file tmp-name)
             (should-error
@@ -2762,9 +2706,9 @@ This checks also `file-name-as-directory', `file-name-directory',
             ;; `tramp-test39-make-lock-file-name'.
 
             ;; Do not overwrite if excluded.
-            (cl-letf (((symbol-function #'y-or-n-p) #'tramp-compat-always)
+            (cl-letf (((symbol-function #'y-or-n-p) #'always)
                       ;; Ange-FTP.
-                      ((symbol-function #'yes-or-no-p) #'tramp-compat-always))
+                      ((symbol-function #'yes-or-no-p) #'always))
               (write-region "foo" nil tmp-name nil nil nil 'mustbenew))
             (should-error
              (cl-letf (((symbol-function #'y-or-n-p) #'ignore)
@@ -2831,8 +2775,6 @@ This checks also `file-name-as-directory', `file-name-directory',
   (skip-unless (tramp--test-enabled))
   (skip-unless (not (tramp--test-ange-ftp-p)))
   (skip-unless (executable-find "gzip"))
-  ;; The function was introduced in Emacs 28.1.
-  (skip-unless (boundp 'tar-goto-file))
 
   (let* ((default-directory ert-remote-temporary-file-directory)
          (archive (ert-resource-file "foo.tar.gz"))
@@ -2846,8 +2788,7 @@ This checks also `file-name-as-directory', `file-name-directory',
           (copy-file archive tmp-file 'ok)
           ;; Read archive.  Check contents of foo.txt, and modify it.  Save.
           (with-current-buffer (setq buffer1 (find-file-noselect tmp-file))
-            ;; The function was introduced in Emacs 28.1.
-            (with-no-warnings (should (tar-goto-file "foo.txt")))
+            (should (tar-goto-file "foo.txt"))
             (save-current-buffer
               (setq buffer2 (tar-extract))
               (should (string-equal (buffer-string) "foo\n"))
@@ -2864,8 +2805,7 @@ This checks also `file-name-as-directory', `file-name-directory',
           (kill-buffer buffer2)
           ;; Read archive.  Check contents of modified foo.txt.
           (with-current-buffer (setq buffer1 (find-file-noselect tmp-file))
-            ;; The function was introduced in Emacs 28.1.
-            (with-no-warnings (should (tar-goto-file "foo.txt")))
+            (should (tar-goto-file "foo.txt"))
             (save-current-buffer
               (setq buffer2 (tar-extract))
               (should (string-equal (buffer-string) "foo\nbar\n")))))
@@ -3304,46 +3244,45 @@ This tests also `file-directory-p' and `file-accessible-directory-p'."
           (delete-directory tmp-name1 'recursive)
           (delete-directory tmp-name2 'recursive)))
 
-      ;; Copy symlink to directory.  Implemented since Emacs 28.1.
-      (when (boundp 'copy-directory-create-symlink)
-        (dolist (copy-directory-create-symlink '(nil t))
-          (unwind-protect
-              (tramp--test-ignore-make-symbolic-link-error
-                ;; Copy to file name.
-                (make-directory tmp-name1)
-                (write-region "foo" nil tmp-name4)
-                (make-symbolic-link tmp-name1 tmp-name7)
-                (should (file-directory-p tmp-name1))
-                (should (file-exists-p tmp-name4))
-                (should (file-symlink-p tmp-name7))
-                (copy-directory tmp-name7 tmp-name2)
-                (if copy-directory-create-symlink
-                    (should
-                     (string-equal
-                      (file-symlink-p tmp-name2) (file-symlink-p tmp-name7)))
-                  (should (file-directory-p tmp-name2)))
-                ;; Copy to directory name.
-                (delete-directory tmp-name2 'recursive)
-                (make-directory tmp-name2)
-                (should (file-directory-p tmp-name2))
-                (copy-directory tmp-name7 (file-name-as-directory tmp-name2))
-                (if copy-directory-create-symlink
-                    (should
-                     (string-equal
-                      (file-symlink-p
-                       (expand-file-name
-                        (file-name-nondirectory tmp-name7) tmp-name2))
-                      (file-symlink-p tmp-name7)))
-                  (should
-                   (file-directory-p
+      ;; Copy symlink to directory.
+      (dolist (copy-directory-create-symlink '(nil t))
+        (unwind-protect
+            (tramp--test-ignore-make-symbolic-link-error
+             ;; Copy to file name.
+             (make-directory tmp-name1)
+             (write-region "foo" nil tmp-name4)
+             (make-symbolic-link tmp-name1 tmp-name7)
+             (should (file-directory-p tmp-name1))
+             (should (file-exists-p tmp-name4))
+             (should (file-symlink-p tmp-name7))
+             (copy-directory tmp-name7 tmp-name2)
+             (if copy-directory-create-symlink
+                 (should
+                  (string-equal
+                   (file-symlink-p tmp-name2) (file-symlink-p tmp-name7)))
+               (should (file-directory-p tmp-name2)))
+             ;; Copy to directory name.
+             (delete-directory tmp-name2 'recursive)
+             (make-directory tmp-name2)
+             (should (file-directory-p tmp-name2))
+             (copy-directory tmp-name7 (file-name-as-directory tmp-name2))
+             (if copy-directory-create-symlink
+                 (should
+                  (string-equal
+                   (file-symlink-p
                     (expand-file-name
-                     (file-name-nondirectory tmp-name7) tmp-name2)))))
+                     (file-name-nondirectory tmp-name7) tmp-name2))
+                   (file-symlink-p tmp-name7)))
+               (should
+                (file-directory-p
+                 (expand-file-name
+                  (file-name-nondirectory tmp-name7) tmp-name2)))))
 
-            ;; Cleanup.
-            (ignore-errors
-              (delete-directory tmp-name1 'recursive)
-              (delete-directory tmp-name2 'recursive)
-              (delete-directory tmp-name7 'recursive))))))))
+          ;; Cleanup.
+          (ignore-errors
+            (delete-directory tmp-name1 'recursive)
+            (delete-directory tmp-name2 'recursive)
+            (delete-directory tmp-name7 'recursive)))))))
 
 (ert-deftest tramp-test16-directory-files ()
   "Check `directory-files'."
@@ -3376,14 +3315,12 @@ This tests also `file-directory-p' and `file-accessible-directory-p'."
             (should (equal (directory-files
                             tmp-name1 'full directory-files-no-dot-files-regexp)
                            `(,tmp-name2 ,tmp-name3)))
-            ;; Check the COUNT arg.  It exists since Emacs 28.
-            (when (tramp--test-emacs28-p)
-              (with-no-warnings
-                (should
-                 (equal
-                  (directory-files
-                   tmp-name1 nil directory-files-no-dot-files-regexp nil 1)
-                  '("bla"))))))
+            ;; Check the COUNT arg.
+            (should
+             (equal
+              (directory-files
+               tmp-name1 nil directory-files-no-dot-files-regexp nil 1)
+              '("bla"))))
 
         ;; Cleanup.
         (ignore-errors (delete-directory tmp-name1 'recursive))))))
@@ -4096,12 +4033,10 @@ They might differ only in time attributes or directory size."
                         tmp-name2 nil (rx bos "b")))
             (should (equal (mapcar #'car attr) '("bar" "boz")))
 
-            ;; Check the COUNT arg.  It exists since Emacs 28.
-            (when (tramp--test-emacs28-p)
-              (with-no-warnings
-                (setq attr (directory-files-and-attributes
-                            tmp-name2 nil (rx bos "b") nil nil 1))
-                (should (equal (mapcar #'car attr) '("bar"))))))
+            ;; Check the COUNT arg.
+            (setq attr (directory-files-and-attributes
+                        tmp-name2 nil (rx bos "b") nil nil 1))
+            (should (equal (mapcar #'car attr) '("bar"))))
 
         ;; Cleanup.
         (ignore-errors (delete-directory tmp-name1 'recursive))))))
@@ -4141,12 +4076,10 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
                 (or (zerop (file-attribute-user-id (file-attributes tmp-name1)))
                     (tramp--test-sshfs-p))
               (should-not (file-writable-p tmp-name1)))
-            ;; Check the NOFOLLOW arg.  It exists since Emacs 28.  For
-            ;; regular files, there shouldn't be a difference.
-            (when (tramp--test-emacs28-p)
-              (with-no-warnings
-                (set-file-modes tmp-name1 #o222 'nofollow)
-                (should (= (file-modes tmp-name1 'nofollow) #o222))))
+            ;; Check the NOFOLLOW arg.  For regular files, there
+            ;; shouldn't be a difference.
+            (set-file-modes tmp-name1 #o222 'nofollow)
+            (should (= (file-modes tmp-name1 'nofollow) #o222))
             ;; Setting the mode for not existing files shall fail.
             (should-error
              (set-file-modes tmp-name2 #o777)
@@ -4155,15 +4088,13 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
         ;; Cleanup.
         (ignore-errors (delete-file tmp-name1)))
 
-      ;; Check the NOFOLLOW arg.  It exists since Emacs 28.  It is
-      ;; implemented for tramp-gvfs.el and tramp-sh.el.  However,
-      ;; tramp-gvfs,el does not support creating symbolic links.  And
-      ;; in tramp-sh.el, we must ensure that the remote chmod command
-      ;; supports the "-h" argument.
-      (when (and (tramp--test-emacs28-p) (tramp--test-sh-p)
-                 (tramp-get-remote-chmod-h tramp-test-vec))
+      ;; Check the NOFOLLOW arg.  It is implemented for tramp-gvfs.el
+      ;; and tramp-sh.el.  However, tramp-gvfs,el does not support
+      ;; creating symbolic links.  And in tramp-sh.el, we must ensure
+      ;; that the remote chmod command supports the "-h" argument.
+      (when (and (tramp--test-sh-p) (tramp-get-remote-chmod-h tramp-test-vec))
         (unwind-protect
-            (with-no-warnings
+            (progn
               (write-region "foo" nil tmp-name1)
               (should (file-exists-p tmp-name1))
               (make-symbolic-link tmp-name1 tmp-name2)
@@ -4256,7 +4187,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
                 (should-error
                  (make-symbolic-link tmp-name1 tmp-name2 0)
                  :type 'file-already-exists)))
-            (cl-letf (((symbol-function #'yes-or-no-p) #'tramp-compat-always))
+            (cl-letf (((symbol-function #'yes-or-no-p) #'always))
               (make-symbolic-link tmp-name1 tmp-name2 0)
               (should
                (string-equal
@@ -4336,7 +4267,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
                (should-error
                 (add-name-to-file tmp-name1 tmp-name2 0)
                 :type 'file-already-exists))
-             (cl-letf (((symbol-function #'yes-or-no-p) #'tramp-compat-always))
+             (cl-letf (((symbol-function #'yes-or-no-p) #'always))
                (add-name-to-file tmp-name1 tmp-name2 0)
                (should (file-regular-p tmp-name2)))
              (add-name-to-file tmp-name1 tmp-name2 'ok-if-already-exists)
@@ -4548,16 +4479,13 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
               ;; `tmp-name3' does not exist.
               (should (file-newer-than-file-p tmp-name2 tmp-name3))
               (should-not (file-newer-than-file-p tmp-name3 tmp-name1))
-              ;; Check the NOFOLLOW arg.  It exists since Emacs 28.  For
-              ;; regular files, there shouldn't be a difference.
-              (when (tramp--test-emacs28-p)
-                (with-no-warnings
-                  (set-file-times tmp-name1 (seconds-to-time 60) 'nofollow)
-                  (should
-                   (time-equal-p
-                    (file-attribute-modification-time
-                     (file-attributes tmp-name1))
-                    (seconds-to-time 60)))))))
+              ;; Check the NOFOLLOW arg.  For regular files, there
+              ;; shouldn't be a difference.
+              (set-file-times tmp-name1 (seconds-to-time 60) 'nofollow)
+              (should
+               (time-equal-p
+                (file-attribute-modification-time (file-attributes tmp-name1))
+                (seconds-to-time 60)))))
 
         ;; Cleanup.
         (ignore-errors
@@ -4890,8 +4818,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
               ;; Ange-FTP does not support this.
               (unless (tramp--test-ange-ftp-p)
                 (should-not
-                 (file-name-completion
-                  "a" (tramp-compat-file-name-concat tmp-name "fuzz"))))
+                 (file-name-completion "a" (file-name-concat tmp-name "fuzz"))))
               ;; Ange-FTP does not support predicates.
               (unless (tramp--test-ange-ftp-p)
                 (should
@@ -5219,7 +5146,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
                   (goto-char (point-min))
                   (while (search-forward-regexp
                           ansi-color-control-seq-regexp nil t)
-                    (replace-match "" nil nil))
+                    (replace-match ""))
                   (should
                    (string-equal (if destination (format "%s\n" fnnd) "")
                                  (buffer-string)))
@@ -5234,7 +5161,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
                   (goto-char (point-min))
                   (while (search-forward-regexp
                           ansi-color-control-seq-regexp nil t)
-                    (replace-match "" nil nil))
+                    (replace-match ""))
                   (should
                    (string-equal
                     (if destination (format "%s\n%s\n" fnnd fnnd) "")
@@ -5480,7 +5407,7 @@ If UNSTABLE is non-nil, the test is tagged as `:unstable'."
        ;; We do expect an established connection already,
        ;; `file-truename' does it by side-effect.  Suppress
        ;; `tramp--test-enabled', in order to keep the connection.
-       (cl-letf (((symbol-function #'tramp--test-enabled) #'tramp-compat-always))
+       (cl-letf (((symbol-function #'tramp--test-enabled) #'always))
          (file-truename ert-remote-temporary-file-directory)
          (funcall (ert-test-body ert-test))))))
 
@@ -5906,7 +5833,7 @@ If UNSTABLE is non-nil, the test is tagged as `:unstable'."
   (when-let ((default-directory ert-remote-temporary-file-directory)
              (mi (memory-info)))
     (should (consp mi))
-    (should (tramp-compat-length= mi 4))
+    (should (length= mi 4))
     (dotimes (i (length mi))
       (should (natnump (nth i mi))))))
 
@@ -5967,7 +5894,7 @@ INPUT, if non-nil, is a string sent to the process."
               ;; "ls" could produce colorized output.
               (goto-char (point-min))
               (while (search-forward-regexp ansi-color-control-seq-regexp nil t)
-                (replace-match "" nil nil))
+                (replace-match ""))
               (should
                (string-equal
                 (format "%s\n" (file-name-nondirectory tmp-name))
@@ -6303,8 +6230,7 @@ INPUT, if non-nil, is a string sent to the process."
           ;; `local-variable' is buffer-local due to explicit setting.
           ;; We need `with-no-warnings', because `defvar-local' is not
           ;; called at toplevel.
-          (with-no-warnings
-           (defvar-local local-variable 'buffer))
+          (with-no-warnings (defvar-local local-variable 'buffer))
           (with-temp-buffer
             (should (eq local-variable 'buffer)))
 
@@ -6486,7 +6412,7 @@ INPUT, if non-nil, is a string sent to the process."
           (unless (tramp--test-container-oob-p)
             (make-directory tmp-name)
             (should (file-directory-p tmp-name))
-            (while (tramp-compat-length< (string-join orig-exec-path ":") 5000)
+            (while (length< (string-join orig-exec-path ":") 5000)
               (let ((dir (make-temp-file
                           (file-name-as-directory tmp-name) 'dir)))
                 (should (file-directory-p dir))
@@ -6503,7 +6429,7 @@ INPUT, if non-nil, is a string sent to the process."
             ;; Ignore trailing newline.
             (setq path (substring (shell-command-to-string "echo $PATH") nil -1))
             ;; The shell doesn't handle such long strings.
-            (unless (tramp-compat-length>
+            (unless (length>
                      path
                      (tramp-get-connection-property
                       tramp-test-vec "pipe-buf" 4096))
@@ -6707,8 +6633,7 @@ INPUT, if non-nil, is a string sent to the process."
                      :type 'file-error))
                   (tramp-cleanup-connection
                    tramp-test-vec 'keep-debug 'keep-password)
-                  (cl-letf (((symbol-function #'yes-or-no-p)
-                             #'tramp-compat-always))
+                  (cl-letf (((symbol-function #'yes-or-no-p) #'always))
                     (should (stringp (make-auto-save-file-name))))))))
 
         ;; Cleanup.
@@ -6854,25 +6779,18 @@ INPUT, if non-nil, is a string sent to the process."
                  :type 'file-error))
               (tramp-cleanup-connection
                tramp-test-vec 'keep-debug 'keep-password)
-              (cl-letf (((symbol-function #'yes-or-no-p) #'tramp-compat-always))
+              (cl-letf (((symbol-function #'yes-or-no-p) #'always))
                 (should (stringp (car (find-backup-file-name tmp-name1)))))))
 
         ;; Cleanup.
         (ignore-errors (delete-file tmp-name1))
         (tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password)))))
 
-;; The functions were introduced in Emacs 28.1.
 (ert-deftest tramp-test39-make-lock-file-name ()
   "Check `make-lock-file-name', `lock-file', `unlock-file' and `file-locked-p'."
   (skip-unless (tramp--test-enabled))
   (skip-unless (not (tramp--test-ange-ftp-p)))
-  ;; Since Emacs 28.1.
-  (skip-unless (and (fboundp 'lock-file) (fboundp 'unlock-file)))
-  (skip-unless (and (fboundp 'file-locked-p) (fboundp 'make-lock-file-name)))
 
-  ;; `lock-file', `unlock-file', `file-locked-p' and
-  ;; `make-lock-file-name' exist since Emacs 28.1.  We don't want to
-  ;; see compiler warnings for older Emacsen.
   (dolist (quoted (if (tramp--test-expensive-test-p) '(nil t) '(nil)))
     (let ((tmp-name1 (tramp--test-make-temp-name nil quoted))
           (tmp-name2 (tramp--test-make-temp-name nil quoted))
@@ -6889,13 +6807,13 @@ INPUT, if non-nil, is a string sent to the process."
       (unwind-protect
           (progn
             ;; A simple file lock.
-            (should-not (with-no-warnings (file-locked-p tmp-name1)))
-            (with-no-warnings (lock-file tmp-name1))
-            (should (eq (with-no-warnings (file-locked-p tmp-name1)) t))
+            (should-not (file-locked-p tmp-name1))
+            (lock-file tmp-name1)
+            (should (eq (file-locked-p tmp-name1) t))
 
             ;; If it is locked already, nothing changes.
-            (with-no-warnings (lock-file tmp-name1))
-            (should (eq (with-no-warnings (file-locked-p tmp-name1)) t))
+            (lock-file tmp-name1)
+            (should (eq (file-locked-p tmp-name1) t))
 
             ;; `save-buffer' removes the lock.
             (with-temp-buffer
@@ -6904,11 +6822,11 @@ INPUT, if non-nil, is a string sent to the process."
               (should (buffer-modified-p))
               (save-buffer)
               (should-not (buffer-modified-p)))
-            (should-not (with-no-warnings (file-locked-p tmp-name1)))
+            (should-not (file-locked-p tmp-name1))
 
             ;; `kill-buffer' removes the lock.
-            (with-no-warnings (lock-file tmp-name1))
-            (should (eq (with-no-warnings (file-locked-p tmp-name1)) t))
+            (lock-file tmp-name1)
+            (should (eq (file-locked-p tmp-name1) t))
             (with-temp-buffer
               (set-visited-file-name tmp-name1)
               (insert "foo")
@@ -6916,12 +6834,12 @@ INPUT, if non-nil, is a string sent to the process."
               (cl-letf (((symbol-function #'read-from-minibuffer)
                          (lambda (&rest _args) "yes")))
                 (kill-buffer)))
-            (should-not (with-no-warnings (file-locked-p tmp-name1)))
+            (should-not (file-locked-p tmp-name1))
 
             ;; `kill-buffer' should not remove the lock when the
             ;; connection is broken.  See Bug#61663.
-            (with-no-warnings (lock-file tmp-name1))
-            (should (eq (with-no-warnings (file-locked-p tmp-name1)) t))
+            (lock-file tmp-name1)
+            (should (eq (file-locked-p tmp-name1) t))
             (with-temp-buffer
               (set-visited-file-name tmp-name1)
               (insert "foo")
@@ -6934,13 +6852,13 @@ INPUT, if non-nil, is a string sent to the process."
             ;; A new connection changes process id, and also the
             ;; lock file contents.  But it still exists.
             (tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password)
-            (should (stringp (with-no-warnings (file-locked-p tmp-name1))))
+            (should (stringp (file-locked-p tmp-name1)))
 
             ;; When `remote-file-name-inhibit-locks' is set, nothing happens.
             (tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password)
             (let ((remote-file-name-inhibit-locks t))
-              (with-no-warnings (lock-file tmp-name1))
-              (should-not (with-no-warnings (file-locked-p tmp-name1))))
+              (lock-file tmp-name1)
+              (should-not (file-locked-p tmp-name1)))
 
             ;; When `lock-file-name-transforms' is set, another lock
             ;; file is used.
@@ -6948,32 +6866,31 @@ INPUT, if non-nil, is a string sent to the process."
             (let ((lock-file-name-transforms `((,(rx (* nonl)) ,tmp-name2))))
               (should
                (string-equal
-                (with-no-warnings (make-lock-file-name tmp-name1))
-                (with-no-warnings (make-lock-file-name tmp-name2))))
-              (with-no-warnings (lock-file tmp-name1))
-              (should (eq (with-no-warnings (file-locked-p tmp-name1)) t))
-              (with-no-warnings (unlock-file tmp-name1))
-              (should-not (with-no-warnings (file-locked-p tmp-name1))))
+                 (make-lock-file-name tmp-name1)
+                 (make-lock-file-name tmp-name2)))
+              (lock-file tmp-name1)
+              (should (eq (file-locked-p tmp-name1) t))
+              (unlock-file tmp-name1)
+              (should-not (file-locked-p tmp-name1)))
 
             ;; Steal the file lock.
             (tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password)
             (cl-letf (((symbol-function #'read-char) (lambda (&rest _args) ?s)))
-              (with-no-warnings (lock-file tmp-name1)))
-            (should (eq (with-no-warnings (file-locked-p tmp-name1)) t))
+              (lock-file tmp-name1))
+            (should (eq (file-locked-p tmp-name1) t))
 
             ;; Ignore the file lock.
             (tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password)
             (cl-letf (((symbol-function #'read-char) (lambda (&rest _args) ?p)))
-              (with-no-warnings (lock-file tmp-name1)))
-            (should (stringp (with-no-warnings (file-locked-p tmp-name1))))
+              (lock-file tmp-name1))
+            (should (stringp (file-locked-p tmp-name1)))
 
             ;; Quit the file lock machinery.
             (tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password)
             (cl-letf (((symbol-function #'read-char) (lambda (&rest _args) ?q)))
-              (with-no-warnings
-                (should-error
-                 (lock-file tmp-name1)
-                 :type 'file-locked))
+              (should-error
+               (lock-file tmp-name1)
+               :type 'file-locked)
               ;; The same for `write-region'.
               (should-error
                (write-region "foo" nil tmp-name1)
@@ -6986,14 +6903,14 @@ INPUT, if non-nil, is a string sent to the process."
                 (should-error
                  (set-visited-file-name tmp-name1)
                  :type 'file-locked)))
-            (should (stringp (with-no-warnings (file-locked-p tmp-name1)))))
+            (should (stringp (file-locked-p tmp-name1))))
 
         ;; Cleanup.
         (ignore-errors (delete-file tmp-name1))
-        (with-no-warnings (unlock-file tmp-name1))
-        (with-no-warnings (unlock-file tmp-name2))
-        (should-not (with-no-warnings (file-locked-p tmp-name1)))
-        (should-not (with-no-warnings (file-locked-p tmp-name2))))
+        (unlock-file tmp-name1)
+        (unlock-file tmp-name2)
+        (should-not (file-locked-p tmp-name1))
+        (should-not (file-locked-p tmp-name2)))
 
       (unwind-protect
           ;; Create temporary file.  This shall check for sensible
@@ -7010,20 +6927,17 @@ INPUT, if non-nil, is a string sent to the process."
                  :type 'file-error))
               (tramp-cleanup-connection
                tramp-test-vec 'keep-debug 'keep-password)
-              (cl-letf (((symbol-function #'yes-or-no-p) #'tramp-compat-always))
+              (cl-letf (((symbol-function #'yes-or-no-p) #'always))
                 (write-region "foo" nil tmp-name1))))
 
         ;; Cleanup.
         (ignore-errors (delete-file tmp-name1))
         (tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password)))))
 
-;; The functions were introduced in Emacs 28.1.
 (ert-deftest tramp-test39-detect-external-change ()
   "Check that an external file modification is reported."
   (skip-unless (tramp--test-enabled))
   (skip-unless (not (tramp--test-ange-ftp-p)))
-  ;; Since Emacs 28.1.
-  (skip-unless (and (fboundp 'lock-file) (fboundp 'file-locked-p)))
 
   (dolist (quoted (if (tramp--test-expensive-test-p) '(nil t) '(nil)))
     (dolist (create-lockfiles '(nil t))
@@ -7081,8 +6995,7 @@ INPUT, if non-nil, is a string sent to the process."
                         (should (file-locked-p tmp-name)))))
 
                   ;; `save-buffer' removes the file lock.
-                  (cl-letf (((symbol-function #'yes-or-no-p)
-                             #'tramp-compat-always)
+                  (cl-letf (((symbol-function #'yes-or-no-p) #'always)
                             ((symbol-function #'read-char-choice)
                              (lambda (&rest _) ?y)))
                     (should (buffer-modified-p))
@@ -7127,12 +7040,6 @@ INPUT, if non-nil, is a string sent to the process."
     (delete-directory tmp-file)
     (should-not (file-exists-p tmp-file))))
 
-(defun tramp--test-emacs28-p ()
-  "Check for Emacs version >= 28.1.
-Some semantics has been changed for there, without new functions
-or variables, so we check the Emacs version directly."
-  (>= emacs-major-version 28))
-
 (defun tramp--test-emacs29-p ()
   "Check for Emacs version >= 29.1.
 Some semantics has been changed for there, without new functions
@@ -7729,7 +7636,7 @@ This requires restrictions of file name syntax."
 
   (when-let ((fsi (file-system-info ert-remote-temporary-file-directory)))
     (should (consp fsi))
-    (should (tramp-compat-length= fsi 3))
+    (should (length= fsi 3))
     (dotimes (i (length fsi))
       (should (natnump (or (nth i fsi) 0))))))
 
@@ -8322,8 +8229,6 @@ Since it unloads Tramp, it shall be the last test to run."
               (macrop x))
           (string-prefix-p "tramp" (symbol-name x))
           (string-match-p (rx bol "with" (| "tramp" "parsed")) (symbol-name x))
-          ;; `tramp-completion-mode' is autoloaded in Emacs < 28.1.
-          (not (eq 'tramp-completion-mode x))
           ;; `tramp-register-archive-file-name-handler' is autoloaded
           ;; in Emacs < 29.1.
           (not (eq 'tramp-register-archive-file-name-handler x))