private void ToJasonTest(GoogleVisionApiRequest req)
        {
            String json = req.ToJson();

            Debug.WriteLine(json);

            String base64encoded = String.Concat(new String[] {
                "iVBORw0KGgoAAAANSUhEUgAAAHIAAABUCAIAAADRSvQBAAAAAXNSR0IArs4c6QAAAARnQU1BAACx",
                "jwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAKcSURBVHhe7drRkeowDIVh6qIg6qGaNEMxrCXi",
                "RJYUsxtyMgl7/icwjoO/9XDvDFyeDBBZIZEVElkhkRUSWSGRFRJZIZEVElkhkRUSWSGRFRJZIZEV",
                "ElkhkRUSWSGRFRJZIZEVElkhkRUSWSGRFRJZIZEVElkhIViH26V0G8anY69R2/X+GF+rPe7X8TXN",
                "L3GeAKzVz6nJsHVSQjOgl9lrwsCJ2pxVtIqFmLQknlVHpilxvjbcySqNquZBLbDaGdH83G3Maqi8",
                "q5ezz79NdWPWhtK5Cp2PrL/JQbZPI528/ppA1k7ZeeyfSIHVsW9z3ZA1odHzOI5lcvOYPDIHvcb/",
                "CaQHzrjG12VkHtJnVnb+jDhfm7GmqqVpXNnaglk756Sk0qb/ZLEaWSGRFRJZIZEVElkhkRUSWSGR",
                "FRJZIZEVElkhkRUSWSGRFRJZIZEVElkhkRUSWSFhWYdb87Xh9LOATysLHfv7QwBr8hVrnhGO13TZ",
                "EtayQvZF7sIy7u+9eUc9rfojgVI+PXo9SuF3BR28P7yVNUFYy3ZMutPKNLVwjPqFVSSro3euA326",
                "+KfZMBRrfcf1YbvFdktqsVC6867I/GK55/K0d+qfdQTWNLmgTBoecVrGlRm9uwvQ9ZgfArLA4oRU",
                "Yw2rXNSfsLrjndYuaSm/NmN9r1bWwhzXPVmb0g0LaW1hv1bCTi+FK+zclfAr24nV7clMmFL4OpoZ",
                "SO3KDi3SxjfStnSbj9vns9W/fb/HhlQrM+J+y7RpkltivIPcORnWcYjfQujTKnlUN0G2HPZsBdNk",
                "0XmGeeav1OWb97NDENamhlC2r9UhGciP0YtjKpk0LSbteRbfh2f9l5EVElkhkRUSWSGRFRJZIZEV",
                "ElkhkRUSWSGRFdDz+QOx+Ho/Gya2SgAAAABJRU5ErkJggg=="
            });

            Assert.IsTrue(json.IndexOf(base64encoded) > 0);

            Debug.WriteLine(String.Format("Current directory={0}", Environment.CurrentDirectory));
            using (StreamWriter ws = new StreamWriter("test.json")) {
                Debug.WriteLine("write JSON to a file");
                ws.Write(json);
                ws.Write("xxx");
                ws.Close();
            }
        }
 public void ConstructorTest1()
 {
     var req = new GoogleVisionApiRequest("nonexistent.png");
 }
 public void ConstructorTest2()
 {
     var req = new GoogleVisionApiRequest("small.png");
 }
 public void ConstructorTest0()
 {
     var req = new GoogleVisionApiRequest(new byte[] { 0, 1, 2, 3, 4, 5 });
 }