Improve fontification in bat-mode

* lisp/progmodes/bat-mode.el (bat-font-lock-keywords): Match
word and symbol constituents when looking for variable names
to fontify; also, correct the syntax table and mark the equal
sign (=) character as punctuation.  Improve fontification
accuracy of iteration/positional variables.
(bat-mode): Set comment-start-skip.  (Bug#25541)

* test/lisp/progmodes/bat-mode-tests.el: New file, tests for
bat-mode.el.

lisp/progmodes/bat-mode.el

@@ -82,12 +82,15 @@
          (2 font-lock-constant-face t))
         ("^:[^:].*"
          . 'bat-label-face)
-        ("\\_<\\(defined\\|set\\)\\_>[ \t]*\\(\\w+\\)"
+        ("\\_<\\(defined\\|set\\)\\_>[ \t]*\\(\\(\\sw\\|\\s_\\)+\\)"
          (2 font-lock-variable-name-face))
-        ("%\\(\\w+\\)%?"
+        ("%\\(\\(\\sw\\|\\s_\\)+\\)%"
          (1 font-lock-variable-name-face))
-        ("!\\(\\w+\\)!?"                ; delayed-expansion !variable!
+        ("!\\(\\(\\sw\\|\\s_\\)+\\)!"  ; delayed-expansion !variable!
          (1 font-lock-variable-name-face))
+        ("%%\\(?:~[adfnpstxz]*\\(?:\\$\\(\\(?:\\sw\\|\\s_\\)+\\):\\)?\\)?\\([]!#$&-:?-[_-{}~]\\)"
+         (1 font-lock-variable-name-face nil t) ; PATH expansion
+         (2 font-lock-variable-name-face)) ; iteration variable or positional parameter
         ("[ =][-/]+\\(\\w+\\)"
          (1 font-lock-type-face append))
         (,(concat "\\_<" (regexp-opt COMMANDS) "\\_>") . font-lock-builtin-face)
@@ -130,6 +133,7 @@
     (modify-syntax-entry ?{ "_" table)
     (modify-syntax-entry ?} "_" table)
     (modify-syntax-entry ?\\ "." table)
+    (modify-syntax-entry ?= "." table)
     table))
 
 (defconst bat--syntax-propertize
@@ -175,6 +179,7 @@ with `bat-cmd-help'.  Navigate between sections using `imenu'.
 Run script using `bat-run' and `bat-run-args'.\n
 \\{bat-mode-map}"
   (setq-local comment-start "rem ")
+  (setq-local comment-start-skip "rem[ \t]+")
   (setq-local syntax-propertize-function bat--syntax-propertize)
   (setq-local font-lock-defaults
        '(bat-font-lock-keywords nil t)) ; case-insensitive keywords

test/lisp/progmodes/bat-mode-tests.el

@@ -0,0 +1,86 @@
+;;; bat-mode-tests.el --- Tests for bat-mode.el  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2017 Free Software Foundation, Inc.
+
+;; Author: Vladimir Panteleev <vladimir@thecybershadow.net>
+;; Keywords:
+
+;; 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 <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;
+
+;;; Code:
+
+(require 'ert)
+(require 'bat-mode)
+(require 'htmlfontify)
+
+(defun bat-test-fontify (str)
+  "Fontify STR in `bat-mode' to a HTML string using `htmlfontify' and return it."
+  (with-temp-buffer
+    (insert str)
+    (bat-mode)
+    (let ((hfy-optimizations '(body-text-only merge-adjacent-tags)))
+      (with-current-buffer (htmlfontify-buffer) (buffer-string)))))
+
+(ert-deftest bat-test-fontification-var-decl ()
+  "Test fontification of variable declarations."
+  (should
+   (equal
+    (bat-test-fontify "set a_b-c{d}e=f")
+    "<span class=\"builtin\">set</span> <span class=\"variable-name\">a_b-c{d}e</span>=f")))
+
+(ert-deftest bat-test-fontification-var-exp ()
+  "Test fontification of variable expansions."
+  (should
+   (equal
+    (bat-test-fontify "echo %a_b-c{d}e%")
+    "<span class=\"builtin\">echo</span> %<span class=\"variable-name\">a_b-c{d}e</span>%")))
+
+(ert-deftest bat-test-fontification-var-delayed-exp ()
+  "Test fontification of delayed variable expansions."
+  (should
+   (equal
+    (bat-test-fontify "echo !a_b-c{d}e!")
+    "<span class=\"builtin\">echo</span> !<span class=\"variable-name\">a_b-c{d}e</span>!")))
+
+(ert-deftest bat-test-fontification-iter-var-1 ()
+  "Test fontification of iteration variables."
+  (should
+   (equal
+    (bat-test-fontify "echo %%a\necho %%~dp1\necho %%~$PATH:I")
+    "<span class=\"builtin\">echo</span> %%<span class=\"variable-name\">a</span>
+<span class=\"builtin\">echo</span> %%~dp<span class=\"variable-name\">1</span>
+<span class=\"builtin\">echo</span> %%~$<span class=\"variable-name\">PATH</span>:<span class=\"variable-name\">I</span>")))
+
+(defun bat-test-fill-paragraph (str)
+  "Return the result of invoking `fill-paragraph' on STR in a `bat-mode' buffer."
+  (with-temp-buffer
+    (bat-mode)
+    (insert str)
+    (goto-char 1)
+    (font-lock-ensure)
+    (fill-paragraph)
+    (buffer-string)))
+
+(ert-deftest bat-test-fill-paragraph-comment ()
+  "Test `fill-paragraph' in a comment block."
+  (should (equal (bat-test-fill-paragraph "rem foo\nrem bar\n") "rem foo bar\n")))
+
+(provide 'bat-tests)
+;;; bat-mode-tests.el ends here