test for sync list using interface (#1767)

Assets/Mirror/Tests/Editor/Weaver/WeaverSyncListTests.cs

@@ -158,6 +158,23 @@ public void SyncListGenericStructWithCustomMethods()
             Assert.That(weaverErrors, Is.Empty);
         }
 
+        [Test]
+        public void SyncListErrorForInterface()
+        {
+            Assert.That(CompilationFinishedHook.WeaveFailed, Is.True);
+            string weaverError = @"Mirror\.Weaver error:";
+            string type = @"MirrorTest\.MyInterfaceList";
+            string errorMessage = @"cannot have item of type MirrorTest\.MyInterface\.  Use a type supported by mirror instead";
+            Assert.That(weaverErrors, Has.Some.Match($"{weaverError} {type} {errorMessage}"));
+        }
+
+        [Test]
+        public void SyncListInterfaceWithCustomMethods()
+        {
+            Assert.That(CompilationFinishedHook.WeaveFailed, Is.False);
+            Assert.That(weaverErrors, Is.Empty);
+        }
+
         [Test]
         public void SyncListErrorWhenUsingGenericListInNetworkBehaviour()
         {

Assets/Mirror/Tests/Editor/Weaver/WeaverSyncListTests~/SyncListErrorForInterface.cs

@@ -0,0 +1,15 @@
+using UnityEngine;
+using Mirror;
+
+namespace MirrorTest
+{
+    class SyncListErrorForInterface : NetworkBehaviour
+    {
+        MyInterfaceList Foo;
+    }
+    interface MyInterface
+    {
+        int someNumber { get; set; }
+    }
+    class MyInterfaceList : SyncList<MyInterface> { }
+}

Assets/Mirror/Tests/Editor/Weaver/WeaverSyncListTests~/SyncListInterfaceWithCustomMethods.cs

@@ -0,0 +1,32 @@
+using UnityEngine;
+using Mirror;
+
+namespace MirrorTest
+{
+    class SyncListInterfaceWithCustomMethods : NetworkBehaviour
+    {
+        MyInterfaceList Foo;
+    }
+   
+    interface IMyInterface
+    {
+        int someNumber { get; set; }
+    }
+    
+    class MyUser : IMyInterface
+    {
+        public int someNumber { get; set; }
+    }
+    
+    class MyInterfaceList : SyncList<IMyInterface>
+    {
+        protected override void SerializeItem(NetworkWriter writer, IMyInterface item)
+        {
+            writer.WriteInt32(item.someNumber);
+        }
+        protected override IMyInterface DeserializeItem(NetworkReader reader)
+        {
+            return new MyUser { someNumber = reader.ReadInt32() };
+        }
+    }
+}