Fix and enhance StringConverter() to handle more special characters

nanoFramework.Json.Test/Converters/StringConverterTests.cs

@@ -39,5 +39,43 @@ public void StringConverter_ToJson_Should_ReturnValidData(string value, string e
 
             Assert.AreEqual(expectedValue, convertedValue);
         }
+
+        [TestMethod]
+        [DataRow("Text\\1", "Text\\1")]  // Backslash
+        [DataRow("Text\b1", "Text\b1")]  // Backspace
+        [DataRow("Text\f1", "Text\f1")]  // FormFeed
+        [DataRow("Text\r1", "Text\r1")]  // CarriageReturn
+        [DataRow("Text\"1", "Text\"1")]  // DoubleQuote
+        [DataRow("Text\n1", "Text\n1")]  // Newline
+        [DataRow("Text\t1", "Text\t1")]  // Tab
+        [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();
+            var convertedValue = (string)converter.ToType(value);
+
+            Assert.AreEqual(expectedValue, convertedValue);
+        }
+
+        [TestMethod]
+        [DataRow("Text\\1", "\"Text\\\\1\"")]  // Backslash
+        [DataRow("Text\b1", "\"Text\\b1\"")]  // Backspace
+        [DataRow("Text\f1", "\"Text\\f1\"")]  // FormFeed
+        [DataRow("Text\r1", "\"Text\\r1\"")]  // CarriageReturn
+        [DataRow("Text\"1", "\"Text\\\"1\"")]  // DoubleQuote
+        [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();
+            var convertedValue = converter.ToJson(value);
+
+            Assert.AreEqual(expectedValue, convertedValue);
+        }
     }
 }

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

@@ -15,6 +15,10 @@ internal sealed class StringConverter : IConverter
         {
             {'\n', 'n'},
             {'\r', 'r'},
+            {'\b', 'b' },
+            {'\f', 'f' },
+            {'\t', 't' },
+            {'\\', '\\' },
             {'\"', '"' }
         };
 
@@ -97,8 +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)))