Use lexical-binding in executable.el and add tests

* lisp/progmodes/executable.el: Use lexical-binding.
* test/lisp/progmodes/executable-tests.el: New file.

lisp/progmodes/executable.el

@@ -1,4 +1,4 @@
-;;; executable.el --- base functionality for executable interpreter scripts
+;;; executable.el --- base functionality for executable interpreter scripts  -*- lexical-binding: t -*-
 
 ;; Copyright (C) 1994-1996, 2000-2021 Free Software Foundation, Inc.
 

test/lisp/progmodes/executable-tests.el

@@ -0,0 +1,54 @@
+;;; executable-tests.el --- Tests for executable.el  -*- lexical-binding:t -*-
+
+;; Copyright (C) 2021 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:
+
+;; This file is part of ERT, the Emacs Lisp Regression Testing tool.
+;; See ert.el or the texinfo manual for more details.
+
+;;; Code:
+
+(require 'ert)
+(require 'executable)
+
+(ert-deftest executable-tests-set-magic ()
+  (with-temp-buffer
+    (insert "#!/foo/bar")
+    (executable-set-magic "/bin/bash" nil t t)
+    (should (equal (buffer-string) "#!/bin/bash"))))
+
+(ert-deftest executable-tests-set-magic/with-argument ()
+  (with-temp-buffer
+    (insert "#!/foo/bar")
+    (executable-set-magic "/bin/bash" "--norc" t t)
+    (should (equal (buffer-string) "#!/bin/bash --norc"))))
+
+(ert-deftest executable-tests-set-magic/executable-insert-nil ()
+  (let ((executable-insert nil))
+    (with-temp-buffer
+      (insert "#!/foo/bar")
+      (executable-set-magic "/bin/bash" nil t nil)
+      (should (equal (buffer-string) "#!/foo/bar"))))
+  (let ((executable-insert nil))
+    (with-temp-buffer
+      (insert "#!/foo/bar")
+      (executable-set-magic "/bin/bash" nil t t)
+      (should (equal (buffer-string) "#!/bin/bash")))))
+
+;;; executable-tests.el ends here