7009: endless exception loop starting w/o DISPLAY

Reapplied my fix to has_display from gramps40.

svn: r22910

gramps/gen/constfunc.py

@@ -132,15 +132,15 @@ def has_display():
     temp, sys.argv = sys.argv, sys.argv[:1]
     try:
         from gi.repository import Gtk
+        from gi.repository import Gdk
     except:
         return False
+
     try:
-        test = Gtk.init_check(temp)
+        test = Gtk.init_check(temp) and \
+            Gdk.Display.get_default()
         sys.argv = temp
-        if test:
-            return True
-        else:
-            return False
+        return bool(test)
     except:
         sys.argv = temp
         return False

gramps/gen/test/constfunc_test.py

@@ -0,0 +1,46 @@
+# -*- coding: utf-8 -*-
+#
+# Gramps - a GTK+/GNOME based genealogy program
+#
+# Copyright (C) 2013 Vassilii Khachaturov <vassilii@tarunz.org>
+#
+# This program 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 2 of the License, or
+# (at your option) any later version.
+#
+# This program 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 this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+# $Id$
+
+""" Unittest for constfunc.py """
+
+from __future__ import print_function
+
+import unittest
+from .. import constfunc
+
+from os import environ as env
+
+class Test_has_display(unittest.TestCase):
+    def setUp(self):
+        self.has = constfunc.has_display()
+        self.display_nonempty = env.has_key('DISPLAY') and bool(env['DISPLAY'])
+
+    @unittest.skipUnless(constfunc.lin(), "Written for Linux only...")
+    def test_consistent_with_DISPLAY_env(self):
+        assert self.has == self.display_nonempty, \
+                "has_display(): {}, $DISPLAY: {}".format(
+                        self.has, env['DISPLAY'] if env.has_key('DISPLAY') \
+                                else "(unset)")
+
+if __name__ == "__main__":
+    unittest.main()