Drop face from hi-lock--unused-faces only when used

* lisp/hi-lock.el (hi-lock-set-pattern): If REGEXP is already
highlighted, then push FACE into hi-lock--unused-faces (Bug#26666).
* test/lisp/hi-lock-tests.el (hi-lock-bug26666): Add test.

1 files changed, 40 insertions, 0 deletions

diff --git a/test/lisp/hi-lock-tests.el b/test/lisp/hi-lock-tests.el
new file mode 100644
index 00000000000..2cb662cfaca
--- /dev/null
+++ b/test/lisp/hi-lock-tests.el
@@ -0,0 +1,40 @@
+;;; hi-lock-tests.el --- Tests for hi-lock.el  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2017 Free Software Foundation, Inc.
+
+;; Author: Tino Calancha <tino.calancha@gmail.com>
+;; Keywords:
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'ert)
+(require 'hi-lock)
+
+(ert-deftest hi-lock-bug26666 ()
+  "Test for http://debbugs.gnu.org/26666 ."
+  (let ((faces hi-lock-face-defaults))
+    (with-temp-buffer
+      (insert "a A b B\n")
+      (cl-letf (((symbol-function 'completing-read)
+                   (lambda (prompt coll x y z hist defaults)
+                     (car defaults))))
+        (dotimes (_ 2)
+          (let ((face (hi-lock-read-face-name)))
+            (hi-lock-set-pattern "a" face))))
+      (should (equal hi-lock--unused-faces (cdr faces))))))
+
+(provide 'hi-lock-tests)
+;;; hi-lock-tests.el ends here