fix(number-enum-deserialization): added fixes for nullable enum deserialization with valid values (#53)

Author: asadali214

APIMatic.Core.Test/Utilities/CoreHelperTest.cs

@@ -151,6 +151,40 @@ public void JsonDeserialize_EmptyString()
             Assert.AreEqual(expected, actual);
         }
 
+        [Test]
+        public void JsonDeserialize_EnumString()
+        {
+            var actualNullable = CoreHelper.JsonDeserialize<WorkingDays?>("\"Monday\"");
+            Assert.AreEqual(WorkingDays.Monday, actualNullable);
+
+            var actual = CoreHelper.JsonDeserialize<WorkingDays>("\"Monday\"");
+            Assert.AreEqual(WorkingDays.Monday, actual);
+        }
+
+        [Test]
+        public void JsonDeserialize_EnumStringNullable()
+        {
+            var actual = CoreHelper.JsonDeserialize<WorkingDays?>("null");
+            Assert.AreEqual(null, actual);
+        }
+
+        [Test]
+        public void JsonDeserialize_EnumNumber()
+        {
+            var actualNullable = CoreHelper.JsonDeserialize<MonthNumber?>("3");
+            Assert.AreEqual(MonthNumber.March, actualNullable);
+
+            var actual = CoreHelper.JsonDeserialize<MonthNumber>("3");
+            Assert.AreEqual(MonthNumber.March, actual);
+        }
+
+        [Test]
+        public void JsonDeserialize_EnumNumberNullable()
+        {
+            var actual = CoreHelper.JsonDeserialize<MonthNumber?>("null");
+            Assert.AreEqual(null, actual);
+        }
+
         #endregion
 
         #region AppendQueryParameters

APIMatic.Core/Utilities/Converters/NumberEnumConverter.cs

@@ -10,15 +10,31 @@ public override bool CanConvert(Type objectType)
             return objectType.BaseType.FullName == "System.Enum";
         }
 
+        private Type GetInnerType(Type type)
+        {
+            if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
+            {
+                return type.GenericTypeArguments[0];
+            }
+
+            return type;
+        }
+
         public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
         {
-            if (CanConvert(objectType) && reader.TokenType == JsonToken.Integer)
+            if (reader.TokenType == JsonToken.Null)
+            {
+                return null;
+            }
+
+            var innerType = GetInnerType(objectType);
+            if (CanConvert(innerType) && reader.TokenType == JsonToken.Integer)
             {
-                var value = Convert.ToInt32(reader.Value);
-                return value;
+                var enumValue = Enum.ToObject(innerType, Convert.ToInt32(reader.Value));
+                return enumValue;
             }
 
-            throw new JsonSerializationException($"Invalid type for number enum.");
+            throw new JsonSerializationException($"Invalid type for number enum {innerType.FullName}.");
         }
 
         public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)