Added already deserialized bypass and tests

Added a bypass to return a string that as already been deserialized when it lands at StringConverter.ToType()

Removed portion of string escape character processing in JsonConvert as it was implemented in StringConverter (unicode escaped character processing still remains in JsonConvert)

Added Tests for multiple escaped characters in a string and in an object containing a string property.

Added test case for string converter test for serializing and deserializing strings with multiple escaped characters

Author: mizady

nanoFramework.Json.Test/Converters/StringConverterTests.cs

@@ -51,6 +51,7 @@ public void StringConverter_ToJson_Should_ReturnValidData(string value, string e
         [DataRow("['Text3', 1]", "['Text3', 1]")] // Array
         [DataRow("{\"Text1\" : \"/Text1/\"}", "{\"Text1\" : \"/Text1/\"}")] // Json
         [DataRow("ä", "ä")]  // Unicode
+        [DataRow("\"I:\\\\nano\\\\rpath\\\\to\"", "I:\\nano\\rpath\\to")]
         public void StringConverter_ToType_Should_HandleSpecialCharacters(string value, string expectedValue)
         {
             var converter = new Json.Converters.StringConverter();
@@ -68,6 +69,7 @@ public void StringConverter_ToType_Should_HandleSpecialCharacters(string value,
         [DataRow("Text\n1", "\"Text\\n1\"")]  // Newline
         [DataRow("Text\t1", "\"Text\\t1\"")]  // Tab
         [DataRow("ä", "\"ä\"")]  // Unicode
+        [DataRow("I:\\nano\\rpath\\to", "\"I:\\\\nano\\\\rpath\\\\to\"")]
         public void StringConverter_ToJson_Should_HandleSpecialCharacters(string value, string expectedValue)
         {
             var converter = new Json.Converters.StringConverter();

nanoFramework.Json.Test/JsonSerializerOptionsTests.cs

@@ -387,6 +387,34 @@ public void Can_serialize_and_deserialize_escaped_string()
             Assert.AreEqual(thing.Value, deserialized.Value);
         }
 
+        [TestMethod]
+        public void Can_serialize_and_deserialize_object_containing_string_with_multiple_escaped_characters()
+        {
+            var thing = new ThingWithString
+            {
+                Value = "I:\\Nano\\rApp\\app.pe"
+            };
+
+            var serialized = JsonConvert.SerializeObject(thing);
+            var deserialized = (ThingWithString)JsonConvert.DeserializeObject(serialized, typeof(ThingWithString));
+            Assert.AreEqual(thing.Value, deserialized.Value);
+        }
+
+        [TestMethod]
+        public void Can_serialize_and_deserialize_string_with_multiple_escaped_characters()
+        {
+            var testValue = "I:\\Nano\\rApp\\app.pe";
+            Console.WriteLine("Original: " + testValue);
+
+            var serialized = JsonConvert.SerializeObject(testValue);
+            Console.WriteLine("Serialized: " + serialized);
+
+            var deserialized = (string)JsonConvert.DeserializeObject(serialized, typeof(string));
+            Console.WriteLine("Deserialized: " + deserialized);
+
+            Assert.AreEqual(testValue, deserialized);
+        }
+
         [TestMethod]
         public void Can_serialize_and_deserialize_complex_object()
         {

nanoFramework.Json/Converters/StringConverter.cs

@@ -101,8 +101,18 @@ public object ToType(object value)
                 return value;
             }
 
-            //String by default has escaped \" at beggining and end, just remove them
-            var resultString = sourceString.Substring(1, sourceString.Length - 2);
+            string resultString;
+
+            // String by default has escaped \" at beggining and end, just remove them
+            // if they have already been removed, string has likely already been deserialized,
+            // and if so, then we just return it.
+            if (!sourceString.StartsWith("\"") && !sourceString.EndsWith("\""))
+            {
+                return sourceString;
+            }
+
+            resultString = sourceString.Substring(1, sourceString.Length - 2);
+
             var newString = new StringBuilder();
             //Last character can not be escaped, because it's last one
             for (int i = 0; i < resultString.Length - 1; i++)

nanoFramework.Json/JsonConvert.cs

@@ -1088,32 +1088,38 @@ private static LexToken GetNextTokenInternal(ref int jsonPos, ref byte[] jsonByt
                         return EndToken(sb);
                     }
 
-                    //TODO: replace with a mapping array? This switch is really incomplete.
-                    switch (ch)
+                    if(ch == 'u')
                     {
-                        case 't':
-                            ch = '\t';
-                            break;
-
-                        case 'r':
-                            ch = '\r';
-                            break;
-
-                        case 'n':
-                            ch = '\n';
-                            break;
-
-                        case 'u':
-                            unicodeEncoded = true;
-                            break;
-
-                        case '"':
-                            ch = '"';
-                            break;
-
-                        default:
-                            throw new DeserializationException();
+                        unicodeEncoded = true;
                     }
+
+                    //TODO: replace with a mapping array? This switch is really incomplete.
+                    // Has been moved to StringConverter but unicode part still remains here
+                    //switch (ch)
+                    //{
+                    //    case 't':
+                    //        ch = '\t';
+                    //        break;
+
+                    //    case 'r':
+                    //        ch = '\r';
+                    //        break;
+
+                    //    case 'n':
+                    //        ch = '\n';
+                    //        break;
+
+                    //    case 'u':
+                    //        unicodeEncoded = true;
+                    //        break;
+
+                    //    case '"':
+                    //        ch = '"';
+                    //        break;
+
+                    //    default:
+                    //        throw new DeserializationException();
+                    //}
                 }
 
                 if ((sb != null) && ((ch != openQuote) || (escaped)))