4 files changed, 25 insertions, 8 deletions

diff --git a/test/automated/Makefile.in b/test/automated/Makefile.in
index 174b3b6dffe..59a88663e2a 100644
--- a/test/automated/Makefile.in
+++ b/test/automated/Makefile.in
@@ -52,9 +52,15 @@ unexport EMACSDATA EMACSDOC EMACSPATH GREP_OPTIONS
 ## To run tests under a debugger, set this to eg: "gdb --args".
 GDB =
 
+# The locale to run tests under.  Tests should work if this is set to
+# any supported locale.  Use the C locale by default, as it should be
+# supported everywhere.
+TEST_LOCALE = C
+
 # The actual Emacs command run in the targets below.
 # Prevent any setting of EMACSLOADPATH in user environment causing problems.
-emacs = EMACSLOADPATH= LC_ALL=C EMACS_TEST_DIRECTORY=$(srcdir) $(GDB) "$(EMACS)" $(EMACSOPT)
+emacs = EMACSLOADPATH= LC_ALL=$(TEST_LOCALE) EMACS_TEST_DIRECTORY=$(srcdir) \
+ $(GDB) "$(EMACS)" $(EMACSOPT)
 
 .PHONY: all check
 
diff --git a/test/automated/flymake-tests.el b/test/automated/flymake-tests.el
index 23dbb3d010c..a77c31638a5 100644
--- a/test/automated/flymake-tests.el
+++ b/test/automated/flymake-tests.el
@@ -34,6 +34,7 @@
 (defun flymake-tests--current-face (file predicate)
   (let ((buffer (find-file-noselect
                  (expand-file-name file flymake-tests-data-directory)))
+        (process-environment (cons "LC_ALL=C" process-environment))
         (i 0))
     (unwind-protect
         (with-current-buffer buffer
diff --git a/test/automated/python-tests.el b/test/automated/python-tests.el
index 219f99eed62..d9b4c3e1b06 100644
--- a/test/automated/python-tests.el
+++ b/test/automated/python-tests.el
@@ -2920,7 +2920,8 @@ and `python-shell-interpreter-args' in the new shell buffer."
                                    :type 'user-error)))
     (should
      (string= (cadr error-data)
-              "Invalid regexp \\( in `python-shell-prompt-input-regexps'"))))
+              (format-message
+               "Invalid regexp \\( in `python-shell-prompt-input-regexps'")))))
 
 (ert-deftest python-shell-prompt-validate-regexps-2 ()
   "Check `python-shell-prompt-output-regexps' are validated."
@@ -2929,7 +2930,8 @@ and `python-shell-interpreter-args' in the new shell buffer."
                                    :type 'user-error)))
     (should
      (string= (cadr error-data)
-              "Invalid regexp \\( in `python-shell-prompt-output-regexps'"))))
+              (format-message
+               "Invalid regexp \\( in `python-shell-prompt-output-regexps'")))))
 
 (ert-deftest python-shell-prompt-validate-regexps-3 ()
   "Check `python-shell-prompt-regexp' is validated."
@@ -2938,7 +2940,8 @@ and `python-shell-interpreter-args' in the new shell buffer."
                                    :type 'user-error)))
     (should
      (string= (cadr error-data)
-              "Invalid regexp \\( in `python-shell-prompt-regexp'"))))
+              (format-message
+               "Invalid regexp \\( in `python-shell-prompt-regexp'")))))
 
 (ert-deftest python-shell-prompt-validate-regexps-4 ()
   "Check `python-shell-prompt-block-regexp' is validated."
@@ -2947,7 +2950,8 @@ and `python-shell-interpreter-args' in the new shell buffer."
                                    :type 'user-error)))
     (should
      (string= (cadr error-data)
-              "Invalid regexp \\( in `python-shell-prompt-block-regexp'"))))
+              (format-message
+               "Invalid regexp \\( in `python-shell-prompt-block-regexp'")))))
 
 (ert-deftest python-shell-prompt-validate-regexps-5 ()
   "Check `python-shell-prompt-pdb-regexp' is validated."
@@ -2956,7 +2960,8 @@ and `python-shell-interpreter-args' in the new shell buffer."
                                    :type 'user-error)))
     (should
      (string= (cadr error-data)
-              "Invalid regexp \\( in `python-shell-prompt-pdb-regexp'"))))
+              (format-message
+               "Invalid regexp \\( in `python-shell-prompt-pdb-regexp'")))))
 
 (ert-deftest python-shell-prompt-validate-regexps-6 ()
   "Check `python-shell-prompt-output-regexp' is validated."
@@ -2965,7 +2970,8 @@ and `python-shell-interpreter-args' in the new shell buffer."
                                    :type 'user-error)))
     (should
      (string= (cadr error-data)
-              "Invalid regexp \\( in `python-shell-prompt-output-regexp'"))))
+              (format-message
+               "Invalid regexp \\( in `python-shell-prompt-output-regexp'")))))
 
 (ert-deftest python-shell-prompt-validate-regexps-7 ()
   "Check default regexps are valid."
@@ -2982,7 +2988,8 @@ and `python-shell-interpreter-args' in the new shell buffer."
                                    :type 'user-error)))
     (should
      (string= (cadr error-data)
-              "Invalid regexp \\( in `python-shell-prompt-output-regexp'"))))
+              (format-message
+               "Invalid regexp \\( in `python-shell-prompt-output-regexp'")))))
 
 (ert-deftest python-shell-prompt-set-calculated-regexps-2 ()
   "Check `python-shell-prompt-input-regexps' are set."
diff --git a/test/automated/tildify-tests.el b/test/automated/tildify-tests.el
index b53f58c279e..788abe7f731 100644
--- a/test/automated/tildify-tests.el
+++ b/test/automated/tildify-tests.el
@@ -55,6 +55,7 @@ If IS-XML is non-nil, <pre> tag is not treated specially."
 INPUT is the initial content of the buffer and EXPECTED is expected result
 after `tildify-buffer' is run."
   (with-temp-buffer
+    (setq-local buffer-file-coding-system 'utf-8)
     (dolist (mode modes)
       (erase-buffer)
       (funcall mode)
@@ -187,6 +188,7 @@ The function must terminate as soon as callback returns nil."
 
 (defun tildify-space-test--test (modes nbsp env-open &optional set-space-string)
   (with-temp-buffer
+    (setq-local buffer-file-coding-system 'utf-8)
     (dolist (mode modes)
       (funcall mode)
       (when set-space-string
@@ -226,6 +228,7 @@ The function must terminate as soon as callback returns nil."
 (defun tildify-space-undo-test--test
     (modes nbsp env-open &optional set-space-string)
   (with-temp-buffer
+    (setq-local buffer-file-coding-system 'utf-8)
     (dolist (mode modes)
       (funcall mode)
       (when set-space-string