test: add test-lib.el file with `visible-buffer-string' function

The patch adds test-lib.el file for Emacs tests auxiliary stuff.
Currently, it implements two functions: `visible-buffer-string'
and `visible-buffer-substring'.  These are similar to standard
counterparts without "visible-" prefix but exclude invisible
text.  The functions are not used anywhere at the moment but
should be useful for testing hiding/showing in the Emacs
interface.

Edited-by: Carl Worth <cworth@cworth.org> Fixed "basic" test to ignore
new test-lib.el file.

test/basic

@@ -55,7 +55,7 @@ eval $(sed -n -e '/^TESTS="$/,/^"$/p' notmuch-test ../notmuch-test)
 tests_in_suite=$(for i in $TESTS; do echo $i; done | sort)
 available=$(ls -1 ../ | \
     sed -r -e "/^(aggregate-results.sh|Makefile|Makefile.local|notmuch-test)/d" \
-	   -e "/^(README|test-lib.sh|test-results|tmp.*|valgrind|corpus*)/d" \
+	   -e "/^(README|test-lib.sh|test-lib.el|test-results|tmp.*|valgrind|corpus*)/d" \
 	   -e "/^(emacs.expected-output|smtp-dummy|smtp-dummy.c|test-verbose)/d" \
 	   -e "/^(test.expected-output|.*~)/d" | sort)
 test_expect_equal "$tests_in_suite" "$available"

test/test-lib.el

@@ -0,0 +1,35 @@
+;; test-lib.el --- auxiliary stuff for Notmuch Emacs tests.
+;;
+;; Copyright © Carl Worth
+;; Copyright © David Edmondson
+;;
+;; This file is part of Notmuch test suit.
+;;
+;; Notmuch 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.
+;;
+;; Notmuch 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 Notmuch.  If not, see <http://www.gnu.org/licenses/>.
+;;
+;; Authors: Dmitry Kurochkin <dmitry.kurochkin@gmail.com>
+
+(defun visible-buffer-string ()
+  "Same as `buffer-string', but excludes invisible text."
+  (visible-buffer-substring (point-min) (point-max)))
+
+(defun visible-buffer-substring (start end)
+  "Same as `buffer-substring', but excludes invisible text."
+  (let (str)
+    (while (< start end)
+      (let ((next-pos (next-char-property-change start end)))
+	(when (not (invisible-p start))
+	  (setq str (concat str (buffer-substring start next-pos))))
+	(setq start next-pos)))
+    str))

test/test-lib.sh

@@ -792,9 +792,9 @@ fi
 #
 # --no-site-file	Don't load the site-wide startup stuff
 #
-# --directory		Ensure that the local notmuch.el source is found
+# --directory		Ensure that the local elisp sources are found
 #
-# --load		Force loading of notmuch.el
+# --load		Force loading of notmuch.el and test-lib.el
 #
 # notmuch-test-wait	Function for tests to use to wait for process completion
 #
@@ -804,6 +804,7 @@ fi
 
 emacs \$BATCH --no-init-file --no-site-file \
 	--directory ../../emacs --load notmuch.el \
+	--directory .. --load test-lib.el \
 	--eval "(defun notmuch-test-wait ()
 			(while (get-buffer-process (current-buffer))
 				(sleep-for 0.1)))" \