Use lexical-binding in pcmpl-linux.el and add tests

* lisp/pcmpl-linux.el: Use lexical-binding.
(pcmpl-linux-fs-modules-path-format)
(pcmpl-linux-mtab-file): New constants.
(pcmpl-linux-fs-types, pcmpl-linux-mounted-directories): Use above
new constants.
* test/lisp/pcmpl-linux-resources/fs/ext4/.keep:
* test/lisp/pcmpl-linux-resources/mtab:
* test/lisp/pcmpl-linux-tests.el: New files.

lisp/pcmpl-linux.el

@@ -1,4 +1,4 @@
-;;; pcmpl-linux.el --- functions for dealing with GNU/Linux completions
+;;; pcmpl-linux.el --- functions for dealing with GNU/Linux completions  -*- lexical-binding: t -*-
 
 ;; Copyright (C) 1999-2020 Free Software Foundation, Inc.
 
@@ -65,18 +65,22 @@
   (pcomplete-opt "hVanfFrsvwt(pcmpl-linux-fs-types)o?L?U?")
   (while (pcomplete-here (pcomplete-entries) nil 'identity)))
 
+(defconst pcmpl-linux-fs-modules-path-format "/lib/modules/%s/kernel/fs/")
+
 (defun pcmpl-linux-fs-types ()
   "Return a list of available fs modules on GNU/Linux systems."
   (let ((kernel-ver (pcomplete-process-result "uname" "-r")))
     (directory-files
-     (concat "/lib/modules/" kernel-ver "/kernel/fs/"))))
+     (format pcmpl-linux-fs-modules-path-format kernel-ver))))
+
+(defconst pcmpl-linux-mtab-file "/etc/mtab")
 
 (defun pcmpl-linux-mounted-directories ()
   "Return a list of mounted directory names."
   (let (points)
-    (when (file-readable-p "/etc/mtab")
+    (when (file-readable-p pcmpl-linux-mtab-file)
       (with-temp-buffer
-	(insert-file-contents-literally "/etc/mtab")
+        (insert-file-contents-literally pcmpl-linux-mtab-file)
 	(while (not (eobp))
 	  (let* ((line (buffer-substring (point) (line-end-position)))
 		 (args (split-string line " ")))

test/lisp/pcmpl-linux-resources/mtab

@@ -0,0 +1,11 @@
+/dev/sdb1 / ext3 rw,relatime,errors=remount-ro 0 0
+proc /proc proc rw,noexec,nosuid,nodev 0 0
+/sys /sys sysfs rw,noexec,nosuid,nodev 0 0
+varrun /var/run tmpfs rw,noexec,nosuid,nodev,mode=0755 0 0
+varlock /var/lock tmpfs rw,noexec,nosuid,nodev,mode=1777 0 0
+udev /dev tmpfs rw,mode=0755 0 0
+devshm /dev/shm tmpfs rw 0 0
+devpts /dev/pts devpts rw,gid=5,mode=620 0 0
+lrm /lib/modules/2.6.24-16-generic/volatile tmpfs rw 0 0
+securityfs /sys/kernel/security securityfs rw 0 0
+gvfs-fuse-daemon /home/alice/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,user=alice 0 0

test/lisp/pcmpl-linux-tests.el

@@ -0,0 +1,51 @@
+;;; pcmpl-linux-tests.el --- Tests for pcmpl-linux.el  -*- lexical-binding: t -*-
+
+;; Copyright (C) 2020 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 'ert)
+(require 'pcmpl-linux)
+
+(defvar pcmpl-linux-tests-data-dir
+  (file-truename
+   (expand-file-name "pcmpl-linux-resources/"
+                     (file-name-directory (or load-file-name
+                                              buffer-file-name))))
+  "Base directory of pcmpl-linux-tests.el data files.")
+
+(ert-deftest pcmpl-linux-test-fs-types ()
+  (let ((pcmpl-linux-fs-modules-path-format (expand-file-name "fs"
+                                                   pcmpl-linux-tests-data-dir)))
+    ;; FIXME: Shouldn't return "." and ".."
+    (should (equal (pcmpl-linux-fs-types)
+                   '("." ".." "ext4")))))
+
+(ert-deftest pcmpl-linux-test-mounted-directories ()
+  (let ((pcmpl-linux-mtab-file (expand-file-name "mtab"
+                                      pcmpl-linux-tests-data-dir)))
+    (should (equal (pcmpl-linux-mounted-directories)
+                   '("/" "/dev" "/dev/pts" "/dev/shm" "/home/alice/.gvfs"
+                     "/lib/modules/2.6.24-16-generic/volatile" "/proc" "/sys"
+                     "/sys/kernel/security" "/var/lock" "/var/run")))))
+
+(provide 'pcmpl-linux-tests)
+
+;;; pcmpl-linux-tests.el ends here