Split out unmanaged implementation of RealmLive into its own class

osu.Game/Database/RealmLive.cs

@@ -24,20 +24,16 @@ namespace osu.Game.Database
         /// </summary>
         private readonly T data;
 
-        private readonly RealmContextFactory? realmFactory;
+        private readonly RealmContextFactory realmFactory;
 
         /// <summary>
         /// Construct a new instance of live realm data.
         /// </summary>
         /// <param name="data">The realm data.</param>
         /// <param name="realmFactory">The realm factory the data was sourced from. May be null for an unmanaged object.</param>
-        public RealmLive(T data, RealmContextFactory? realmFactory)
+        public RealmLive(T data, RealmContextFactory realmFactory)
         {
             this.data = data;
-
-            if (IsManaged && realmFactory == null)
-                throw new ArgumentException(@"Realm factory must be provided for a managed instance", nameof(realmFactory));
-
             this.realmFactory = realmFactory;
 
             ID = data.ID;
@@ -55,9 +51,6 @@ namespace osu.Game.Database
                 return;
             }
 
-            if (realmFactory == null)
-                throw new ArgumentException(@"Realm factory must be provided for a managed instance", nameof(realmFactory));
-
             using (var realm = realmFactory.CreateContext())
                 perform(realm.Find<T>(ID));
         }
@@ -74,9 +67,6 @@ namespace osu.Game.Database
             if (!IsManaged)
                 return perform(data);
 
-            if (realmFactory == null)
-                throw new ArgumentException(@"Realm factory must be provided for a managed instance", nameof(realmFactory));
-
             using (var realm = realmFactory.CreateContext())
                 return perform(realm.Find<T>(ID));
         }
@@ -108,7 +98,7 @@ namespace osu.Game.Database
                 if (!ThreadSafety.IsUpdateThread)
                     throw new InvalidOperationException($"Can't use {nameof(Value)} on managed objects from non-update threads");
 
-                return realmFactory!.Context.Find<T>(ID);
+                return realmFactory.Context.Find<T>(ID);
             }
         }
 

osu.Game/Database/RealmLiveUnmanaged.cs

@@ -0,0 +1,44 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using Realms;
+
+#nullable enable
+
+namespace osu.Game.Database
+{
+    /// <summary>
+    /// Provides a method of working with unmanaged realm objects.
+    /// Usually used for testing purposes where the instance is never required to be managed.
+    /// </summary>
+    /// <typeparam name="T">The underlying object type.</typeparam>
+    public class RealmLiveUnmanaged<T> : ILive<T> where T : RealmObjectBase, IHasGuidPrimaryKey
+    {
+        /// <summary>
+        /// Construct a new instance of live realm data.
+        /// </summary>
+        /// <param name="data">The realm data.</param>
+        public RealmLiveUnmanaged(T data)
+        {
+            Value = data;
+        }
+
+        public bool Equals(ILive<T>? other) => ID == other?.ID;
+
+        public Guid ID => Value.ID;
+
+        public void PerformRead(Action<T> perform) => perform(Value);
+
+        public TReturn PerformRead<TReturn>(Func<T, TReturn> perform) => perform(Value);
+
+        public void PerformWrite(Action<T> perform) => throw new InvalidOperationException(@"Can't perform writes on a non-managed underlying value");
+
+        public bool IsManaged => false;
+
+        /// <summary>
+        /// The original live data used to create this instance.
+        /// </summary>
+        public T Value { get; }
+    }
+}

osu.Game/Database/RealmObjectExtensions.cs

@@ -56,13 +56,13 @@ namespace osu.Game.Database
         public static List<ILive<T>> ToLiveUnmanaged<T>(this IEnumerable<T> realmList)
             where T : RealmObject, IHasGuidPrimaryKey
         {
-            return realmList.Select(l => new RealmLive<T>(l, null)).Cast<ILive<T>>().ToList();
+            return realmList.Select(l => new RealmLiveUnmanaged<T>(l)).Cast<ILive<T>>().ToList();
         }
 
         public static ILive<T> ToLiveUnmanaged<T>(this T realmObject)
             where T : RealmObject, IHasGuidPrimaryKey
         {
-            return new RealmLive<T>(realmObject, null);
+            return new RealmLiveUnmanaged<T>(realmObject);
         }
 
         public static List<ILive<T>> ToLive<T>(this IEnumerable<T> realmList, RealmContextFactory realmContextFactory)