diff -r 000000000000 -r 6474c204b198 parser/xml/test/unit/test_namespace_support.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/parser/xml/test/unit/test_namespace_support.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,52 @@
+function noop() {}
+
+function run_test() {
+  var contentHandler = {
+    attrs: null,
+    reset: function() {
+        this.attrs = [];
+    },
+    startDocument: noop,
+    endDocument: noop,
+
+    startElement: function startElement(aNamespaceURI, aLocalName, aNodeName, aAttrs) {
+      for (var i = 0; i < aAttrs.length; i++) 
+        this.attrs.push(aAttrs.getQName(i));
+    },
+
+    endElement: noop,
+    characters: noop,
+    processingInstruction: noop,
+    ignorableWhitespace: noop,
+    startPrefixMapping: noop,
+    endPrefixMapping: noop
+  };
+
+  const nsISAXXMLReader = Components.interfaces.nsISAXXMLReader;
+  const src = "<a:x xmlns:a='foo' y='bar'/>";
+  const NS_PREFIX = "http://xml.org/sax/features/namespace-prefixes";
+
+  var saxReader = Components.classes["@mozilla.org/saxparser/xmlreader;1"]
+                            .createInstance(nsISAXXMLReader);
+  do_check_false(saxReader.getFeature(NS_PREFIX));
+  saxReader.contentHandler = contentHandler;
+  contentHandler.reset();
+  saxReader.parseFromString(src, "application/xml");
+  do_check_eq(contentHandler.attrs.length, 1);
+  do_check_eq(contentHandler.attrs[0], "y");
+
+  saxReader.setFeature(NS_PREFIX, true);
+  do_check_true(saxReader.getFeature(NS_PREFIX));
+  contentHandler.reset();
+  saxReader.parseFromString(src, "application/xml");
+  do_check_eq(contentHandler.attrs.length, 2);
+  do_check_eq(contentHandler.attrs[0], "xmlns:a");
+  do_check_eq(contentHandler.attrs[1], "y");
+
+  saxReader.setFeature(NS_PREFIX, false);
+  do_check_false(saxReader.getFeature(NS_PREFIX));
+  contentHandler.reset();
+  saxReader.parseFromString(src, "application/xml");
+  do_check_eq(contentHandler.attrs.length, 1);
+  do_check_eq(contentHandler.attrs[0], "y");
+}