public void PredefinedNamespaces()
        {
            Assert.AreEqual(Constants.Soap11, ctx.LookupNamespace("s11"), "#1");
            Assert.AreEqual(Constants.Soap12, ctx.LookupNamespace("s12"), "#2");
            // ... only them?

            foreach (char c in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
            {
                Assert.IsNull(ctx.LookupNamespace(c + ""), "char:" + c);
            }

            Assert.IsNull(ctx.LookupNamespace("wsa"), "#3");
            Assert.IsNull(ctx.LookupNamespace("wsu"), "#4");
        }
 public XPathMessageContextMarkupExtension(XPathMessageContext context) : this()
 {
     foreach (string str in context)
     {
         if (!implicitPrefixes.Contains(str))
         {
             this.namespaces.Add(str, context.LookupNamespace(str));
         }
     }
 }