Fix yank-media utf-16 detection

* lisp/yank-media.el (yank-media--utf-16-p): Factor out into its
own function for easier testing and fix the code.

1 files changed, 38 insertions, 0 deletions

diff --git a/test/lisp/yank-media-tests.el b/test/lisp/yank-media-tests.el
new file mode 100644
index 00000000000..4487ae150da
--- /dev/null
+++ b/test/lisp/yank-media-tests.el
@@ -0,0 +1,38 @@
+;;; yank-media-tests.el --- Tests for yank-media.el  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2022 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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.
+
+;; GNU Emacs 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 GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;
+
+;;; Code:
+
+(require 'yank-media)
+(require 'ert)
+(require 'ert-x)
+
+(ert-deftest test-utf-16 ()
+  (should-not (yank-media--utf-16-p "f"))
+  (should-not (yank-media--utf-16-p "fo"))
+  (should-not (yank-media--utf-16-p "\000ofo"))
+  (should (eq (yank-media--utf-16-p "\000o\000o") 'utf-16-be))
+  (should (eq (yank-media--utf-16-p "o\000o\000") 'utf-16-le))
+  (should-not (yank-media--utf-16-p "o\000\000o")))
+
+;;; yank-media-tests.el ends here