Replace (skip-unless nil) by tag :unstable in test packages

* test/lisp/filenotify-tests.el (file-notify--deftest-remote):
Use tag :unstable if SKIP is non-nil.

* test/lisp/net/tramp-tests.el (tramp-test36-vc-registered):
Use ert-skip instead of (skip-unless nil).

* test/lisp/progmodes/python-tests.el
(python-tests--python-nav-end-of-statement--infloop): Use tag
:unstable instead of (skip-unless nil).

3 files changed, 3 insertions, 4 deletions

diff --git a/test/lisp/filenotify-tests.el b/test/lisp/filenotify-tests.el
index 50036209b0f..bf13fc1e857 100644
--- a/test/lisp/filenotify-tests.el
+++ b/test/lisp/filenotify-tests.el
@@ -266,9 +266,8 @@ This returns only for the local case and gfilenotify; otherwise it is nil.
   (declare (indent 1))
   `(ert-deftest ,(intern (concat (symbol-name test) "-remote")) ()
      ,docstring
-     :tags '(:expensive-test)
      :expected-result (or ,expected :passed)
-     (skip-unless (not ,skip))
+     :tags ,(if skip '(:expensive-test :unstable) '(:expensive-test))
      (let* ((temporary-file-directory
              file-notify-test-remote-temporary-file-directory)
             (ert-test (ert-get-test ',test))
diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index 5a9541db8fb..cc3200be948 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -4579,7 +4579,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
               ;; skip the test then.
               (condition-case nil
                   (vc-create-repo (car vc-handled-backends))
-                (error (skip-unless nil)))
+                (error (ert-skip "`vc-create-repo' not supported")))
               ;; The structure of VC-FILESET is not documented.  Let's
               ;; hope it won't change.
               (condition-case nil
diff --git a/test/lisp/progmodes/python-tests.el b/test/lisp/progmodes/python-tests.el
index 999cf8dc7a3..b940f45bb90 100644
--- a/test/lisp/progmodes/python-tests.el
+++ b/test/lisp/progmodes/python-tests.el
@@ -5350,7 +5350,7 @@ buffer with overlapping strings."
   ;; The description of the problem it's trying to catch is not clear enough
   ;; to be able to see if the underlying problem is really fixed, sadly.
   ;; E.g. I don't know what is meant by "overlap", really.
-  (skip-unless nil)
+  :tags '(:unstable)
   (python-tests-with-temp-buffer "''' '\n''' ' '\n"
     (syntax-propertize (point-max))
     ;; Create a situation where strings nominally overlap.  This