test: extract message-capture helper into testutil

Five test files hand-rolled the same scaffolding to capture the echo-area message: a nil-initialized var, a cl-letf on message, and a lambda that stored the formatted string. Centralize it as testutil-wttrin-with-captured-message, which binds the var and captures the last message shown.

Behavior is unchanged. The full suite stays green. Sites that mock message for a different reason are left alone: the ones that silence it with #'ignore, and the one that accumulates every message into a list.

1 files changed, 6 insertions, 9 deletions

diff --git a/tests/test-wttrin-requery-force.el b/tests/test-wttrin-requery-force.el
index d572348..171166d 100644
--- a/tests/test-wttrin-requery-force.el
+++ b/tests/test-wttrin-requery-force.el
@@ -63,15 +63,12 @@
   "When no current location is set, user should be told there's nothing to refresh."
   (test-wttrin-requery-force-setup)
   (unwind-protect
-      (let ((displayed-message nil))
-        (cl-letf (((symbol-function 'message)
-                   (lambda (fmt &rest args)
-                     (setq displayed-message (apply #'format fmt args)))))
-          (with-current-buffer (get-buffer-create "*wttr.in*")
-            ;; wttrin--current-location is nil (buffer-local default)
-            (wttrin-requery-force)
-            (should displayed-message)
-            (should (string-match-p "No location" displayed-message)))))
+      (testutil-wttrin-with-captured-message displayed-message
+        (with-current-buffer (get-buffer-create "*wttr.in*")
+          ;; wttrin--current-location is nil (buffer-local default)
+          (wttrin-requery-force)
+          (should displayed-message)
+          (should (string-match-p "No location" displayed-message))))
     (test-wttrin-requery-force-teardown)))
 
 (ert-deftest test-wttrin-requery-force-boundary-force-flag-does-not-leak ()