Add test for 'with-directory-excursion'.

Makefile.am

@@ -24,7 +24,8 @@ SCM_LOG_DRIVER = \
 
 TESTS = \
   tests/base.scm \
-  tests/database.scm
+  tests/database.scm \
+  tests/utils.scm
 
 # Unset 'GUILE_LOAD_COMPILED_PATH' altogether while compiling.  Otherwise, if
 # $GUILE_LOAD_COMPILED_PATH contains $(cuirassmoduledir), we may find .go

tests/utils.scm

@@ -0,0 +1,39 @@
+;;;; utils.scm -- tests for (cuirass utils) module
+;;;
+;;; Copyright © 2016 Mathieu Lirzin <mthl@gnu.org>
+;;;
+;;; This file is part of Cuirass.
+;;;
+;;; Cuirass 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.
+;;;
+;;; Cuirass 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 Cuirass.  If not, see <http://www.gnu.org/licenses/>.
+
+(use-modules (cuirass utils)
+             (srfi srfi-64))
+
+(define dir-1 (make-parameter ""))
+(define dir-2 (make-parameter ""))
+
+(test-assert "with-directory-excursion"
+  (let ((old (getcwd))
+        (tmp (tmpnam)))
+    (dynamic-wind
+      (λ ()
+        (mkdir tmp))
+      (λ ()
+        (with-directory-excursion tmp
+          (dir-1 (getcwd)))
+        (dir-2 (getcwd))
+        (and (string=? (dir-1) tmp)
+             (string=? (dir-2) old)))
+      (λ ()
+        (rmdir tmp)))))