Keep face available if there are no matches

If font-lock-mode is disabled in the current buffer, and
there are no matches for REGEXP, then keep FACE available
for a next search.
* lisp/hi-lock.el (hi-lock-set-pattern): Add FACE into
hi-lock--unused-faces if font-lock-mode is disabled and
there are no matches.
* test/lisp/hi-lock-tests.el (hi-lock-test-set-pattern): Add test.

1 files changed, 12 insertions, 0 deletions

diff --git a/test/lisp/hi-lock-tests.el b/test/lisp/hi-lock-tests.el
index 2cb662cfaca..9e2401979b0 100644
--- a/test/lisp/hi-lock-tests.el
+++ b/test/lisp/hi-lock-tests.el
@@ -36,5 +36,17 @@
             (hi-lock-set-pattern "a" face))))
       (should (equal hi-lock--unused-faces (cdr faces))))))
 
+(ert-deftest hi-lock-test-set-pattern ()
+  (let ((faces hi-lock-face-defaults))
+    (with-temp-buffer
+      (insert "foo bar")
+      (cl-letf (((symbol-function 'completing-read)
+                 (lambda (prompt coll x y z hist defaults)
+                   (car defaults))))
+        (hi-lock-set-pattern "9999" (hi-lock-read-face-name)) ; No match
+        (hi-lock-set-pattern "foo" (hi-lock-read-face-name)))
+      ;; Only one match, then we have used just 1 face
+      (should (equal hi-lock--unused-faces (cdr faces))))))
+
 (provide 'hi-lock-tests)
 ;;; hi-lock-tests.el ends here