[gxml] Added test to add and remove namespaced attributes

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit d9228d9818065cde4405479f54de1296655f1139
Author: Daniel Espinosa <esodan gmail com>
Date:   Wed Nov 2 17:51:27 2016 -0600

    Added test to add and remove namespaced attributes

 test/GomElementTest.vala |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/test/GomElementTest.vala b/test/GomElementTest.vala
index da35012..bf49b43 100644
--- a/test/GomElementTest.vala
+++ b/test/GomElementTest.vala
@@ -121,6 +121,16 @@ class GomElementTest : GXmlTest  {
                                assert (elem.attributes.size == 2);
                                elem.remove_attribute ("owl");
                                assert (elem.attributes.size == 1);
+
+                               elem.set_attribute_ns ("http://www.w3.org/2000/xmlns/";, "xmlns:gxml",
+                                                                                                             
          "http://www.gnome.org/GXml";);
+                               assert (elem.attributes.size == 2);
+                               elem.set_attribute_ns ("http://www.gnome.org/GXml";, "gxml:xola","Mexico");
+                               assert (elem.attributes.size == 3);
+                               assert (elem.get_attribute_ns ("http://www.gnome.org/GXml";, "xola") == 
"Mexico");
+                               elem.remove_attribute_ns ("http://www.gnome.org/GXml";, "xola");
+                               assert (elem.get_attribute_ns ("http://www.gnome.org/GXml";, "xola") == null);
+                               assert (elem.attributes.size == 2);
                        } catch (GLib.Error e) {
                                Test.message (e.message);
                                assert_not_reached ();