Index: trunk/test/unit/org/openstreetmap/josm/data/PreferencesTest.groovy
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/data/PreferencesTest.groovy	(revision 9828)
+++ trunk/test/unit/org/openstreetmap/josm/data/PreferencesTest.groovy	(revision 9829)
@@ -1,2 +1,3 @@
+// License: GPL. For details, see LICENSE file.
 package org.openstreetmap.josm.data
 
@@ -27,3 +28,15 @@
         assert Main.pref.getDefaultColor("foo").alpha == 0x12
     }
+
+    void testToXml() {
+        assert Main.pref.toXML(true) == String.format(
+            "<?xml version=\"1.0\" encoding=\"UTF-8\"?>%n" +
+            "<preferences xmlns='http://josm.openstreetmap.de/preferences-1.0' version='%d'>%n" +
+            "  <tag key='expert' value='true'/>%n" +
+            "  <tag key='jdk.Arrays.useLegacyMergeSort' value='false'/>%n" +
+            "  <tag key='language' value='en'/>%n" +
+            "  <tag key='osm-server.url' value='http://api06.dev.openstreetmap.org/api'/>%n" +
+            "  <tag key='osm-server.username' value='josm_test'/>%n" +
+            "</preferences>%n", Version.getInstance().getVersion())
+    }
 }