[material graph]Slot serialization test

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Testing/IntegrationTests/SerializationTests.cs

 using System;
 using System.Collections.Generic;
-using System.Linq;
 using NUnit.Framework;
 using UnityEngine;
 using UnityEngine.Graphing;
         {
             [SerializeField]
             public string stringValue;
+
+
+
             [SerializeField]
             public int[] arrayValue;
 
             {
                 SimpleSerializeClass.instance
             };
-            
+
             var serialized = SerializationHelper.Serialize(toSerialize);
             Assert.AreEqual(1, serialized.Count);
 
             Assert.IsInstanceOf<SimpleSerializeClass>(loaded[0]);
             loaded[0].AssertAsReference();
         }
-        
+
+        [Test]
+        public void TestSerializableSlotCanSerialize()
+        {
+            var toSerialize = new List<SerializableSlot>()
+            {
+                new SerializableSlot("InSlot", "InSlot", SlotType.Input, 0),
+                new SerializableSlot("OutSlot", "OutSlot", SlotType.Output, 0),
+            };
+
+            var serialized = SerializationHelper.Serialize(toSerialize);
+            var loaded = SerializationHelper.Deserialize<SerializableSlot>(serialized);
+            Assert.AreEqual(2, loaded.Count);
+
+            Assert.IsInstanceOf<SerializableSlot>(loaded[0]);
+            Assert.IsInstanceOf<SerializableSlot>(loaded[1]);
+
+            Assert.AreEqual("InSlot", loaded[0].name);
+            Assert.AreEqual("InSlot", loaded[0].displayName);
+            Assert.IsTrue(loaded[0].isInputSlot);
+            Assert.AreEqual(0, loaded[0].priority);
+
+            Assert.AreEqual("OutSlot", loaded[1].name);
+            Assert.AreEqual("OutSlot", loaded[1].displayName);
+            Assert.IsTrue(loaded[1].isOutputSlot);
+            Assert.AreEqual(0, loaded[1].priority);
+        }
     }
 }

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Runtime/Implementation/SerializableSlot.cs

 using System;
-using System.Runtime.InteropServices;
 
 namespace UnityEngine.Graphing
 {
         private string m_DisplayName = kNotInit;
 
         [SerializeField]
-        private SlotType m_SlotType;
+        private SlotType m_SlotType = SlotType.Input;
 
         [SerializeField]
         private int m_Priority;
             get { return m_Priority; }
             set { m_Priority = value; } 
         }
+        
+        // used via reflection / serialization after deserialize
+        // to reconstruct this slot.
+        public SerializableSlot()
+        { }
 
         public SerializableSlot(string name, string displayName, SlotType slotType, int priority)
         {
             m_Priority = priority;
         }
-
-        // used via reflection / serialization after deserialize
-        // to reconstruct this slot.
-        protected SerializableSlot()
-        {}
 
         public virtual bool OnGUI()
         {