From 40803f02693efb3ce50abfc4d31a31ad95f97fda Mon Sep 17 00:00:00 2001
From: Deukhoofd <Deukhoofd@gmail.com>
Date: Sun, 29 Dec 2024 13:51:59 +0100
Subject: [PATCH] Support for deep cloning battles and Pokemon

---
 PkmnLib.Dynamic/Models/Battle.cs              |   2 +-
 PkmnLib.Dynamic/Models/BattleChoiceQueue.cs   |   3 +-
 PkmnLib.Dynamic/Models/BattleParty.cs         |   4 +-
 PkmnLib.Dynamic/Models/BattleSide.cs          |   2 +-
 PkmnLib.Dynamic/Models/Choices/TurnChoice.cs  |   3 +-
 PkmnLib.Dynamic/Models/LearnedMove.cs         |   3 +-
 PkmnLib.Dynamic/Models/Pokemon.cs             |   4 +-
 PkmnLib.Dynamic/Models/PokemonParty.cs        |   3 +-
 PkmnLib.Dynamic/ScriptHandling/Script.cs      |   2 +-
 .../ScriptHandling/ScriptContainer.cs         |   3 +-
 PkmnLib.Static/StatisticSet.cs                |   3 +-
 PkmnLib.Static/Utils/DeepClone.cs             | 196 ++++++++++++++++++
 PkmnLib.Tests/Static/DeepCloneTests.cs        | 140 +++++++++++++
 13 files changed, 356 insertions(+), 12 deletions(-)
 create mode 100644 PkmnLib.Static/Utils/DeepClone.cs
 create mode 100644 PkmnLib.Tests/Static/DeepCloneTests.cs

diff --git a/PkmnLib.Dynamic/Models/Battle.cs b/PkmnLib.Dynamic/Models/Battle.cs
index da563a9..a807983 100644
--- a/PkmnLib.Dynamic/Models/Battle.cs
+++ b/PkmnLib.Dynamic/Models/Battle.cs
@@ -11,7 +11,7 @@ namespace PkmnLib.Dynamic.Models;
 /// A battle is a representation of a battle in the Pokemon games. It contains all the information needed
 /// to simulate a battle, and can be used to simulate a battle between two parties.
 /// </summary>
-public interface IBattle : IScriptSource
+public interface IBattle : IScriptSource, IDeepCloneable
 {
     /// <summary>
     /// The library the battle uses for handling.
diff --git a/PkmnLib.Dynamic/Models/BattleChoiceQueue.cs b/PkmnLib.Dynamic/Models/BattleChoiceQueue.cs
index 9087efa..2e47495 100644
--- a/PkmnLib.Dynamic/Models/BattleChoiceQueue.cs
+++ b/PkmnLib.Dynamic/Models/BattleChoiceQueue.cs
@@ -1,5 +1,6 @@
 using PkmnLib.Dynamic.Models.Choices;
 using PkmnLib.Dynamic.ScriptHandling;
+using PkmnLib.Static.Utils;
 
 namespace PkmnLib.Dynamic.Models;
 
@@ -11,7 +12,7 @@ namespace PkmnLib.Dynamic.Models;
 /// It holds several helper functions to change the turn order while doing the execution. This is needed, as several
 /// moves in Pokémon actively mess with this order.
 /// </remarks>
-public class BattleChoiceQueue
+public class BattleChoiceQueue : IDeepCloneable
 {
     private readonly ITurnChoice?[] _choices;
     private int _currentIndex;
diff --git a/PkmnLib.Dynamic/Models/BattleParty.cs b/PkmnLib.Dynamic/Models/BattleParty.cs
index 1ae02d2..93f2701 100644
--- a/PkmnLib.Dynamic/Models/BattleParty.cs
+++ b/PkmnLib.Dynamic/Models/BattleParty.cs
@@ -1,10 +1,12 @@
+using PkmnLib.Static.Utils;
+
 namespace PkmnLib.Dynamic.Models;
 
 /// <summary>
 /// A battle party is a wrapper around a Pokemon party that provides additional functionality for battles.
 /// It indicates for which side and position the party is responsible.
 /// </summary>
-public interface IBattleParty
+public interface IBattleParty : IDeepCloneable
 {
     /// <summary>
     /// The backing Pokemon party.
diff --git a/PkmnLib.Dynamic/Models/BattleSide.cs b/PkmnLib.Dynamic/Models/BattleSide.cs
index 796028e..a0da422 100644
--- a/PkmnLib.Dynamic/Models/BattleSide.cs
+++ b/PkmnLib.Dynamic/Models/BattleSide.cs
@@ -8,7 +8,7 @@ namespace PkmnLib.Dynamic.Models;
 /// <summary>
 /// A side in a battle.
 /// </summary>
-public interface IBattleSide : IScriptSource
+public interface IBattleSide : IScriptSource, IDeepCloneable
 {
     /// <summary>
     /// The index of the side on the battle.
diff --git a/PkmnLib.Dynamic/Models/Choices/TurnChoice.cs b/PkmnLib.Dynamic/Models/Choices/TurnChoice.cs
index 2df1487..6be3be6 100644
--- a/PkmnLib.Dynamic/Models/Choices/TurnChoice.cs
+++ b/PkmnLib.Dynamic/Models/Choices/TurnChoice.cs
@@ -1,11 +1,12 @@
 using PkmnLib.Dynamic.ScriptHandling;
+using PkmnLib.Static.Utils;
 
 namespace PkmnLib.Dynamic.Models.Choices;
 
 /// <summary>
 /// A choice that is made at the beginning of a turn. This can be a switch, flee, item, or pass choice.
 /// </summary>
-public interface ITurnChoice : IScriptSource
+public interface ITurnChoice : IScriptSource, IDeepCloneable
 {
     /// <summary>
     /// The user of the turn choice
diff --git a/PkmnLib.Dynamic/Models/LearnedMove.cs b/PkmnLib.Dynamic/Models/LearnedMove.cs
index 4e60a1d..771eba1 100644
--- a/PkmnLib.Dynamic/Models/LearnedMove.cs
+++ b/PkmnLib.Dynamic/Models/LearnedMove.cs
@@ -1,4 +1,5 @@
 using PkmnLib.Static.Moves;
+using PkmnLib.Static.Utils;
 
 namespace PkmnLib.Dynamic.Models;
 
@@ -42,7 +43,7 @@ public enum MoveLearnMethod
 /// A learned move is the data attached to a Pokemon for a move it has learned. It has information
 /// such as the remaining amount of users, how it has been learned, etc.
 /// </summary>
-public interface ILearnedMove
+public interface ILearnedMove : IDeepCloneable
 {
     /// <summary>
     /// The immutable move information of the move.
diff --git a/PkmnLib.Dynamic/Models/Pokemon.cs b/PkmnLib.Dynamic/Models/Pokemon.cs
index 2111bb7..4aa0bd6 100644
--- a/PkmnLib.Dynamic/Models/Pokemon.cs
+++ b/PkmnLib.Dynamic/Models/Pokemon.cs
@@ -12,7 +12,7 @@ namespace PkmnLib.Dynamic.Models;
 /// <summary>
 /// The data of a Pokemon.
 /// </summary>
-public interface IPokemon : IScriptSource
+public interface IPokemon : IScriptSource, IDeepCloneable
 {
     /// <summary>
     /// The library data of the Pokemon.
@@ -352,7 +352,7 @@ public interface IPokemon : IScriptSource
 /// The data of the Pokémon related to being in a battle.
 /// This is only set when the Pokémon is on the field in a battle.
 /// </summary>
-public interface IPokemonBattleData
+public interface IPokemonBattleData : IDeepCloneable
 {
     /// <summary>
     /// The battle the Pokémon is in.
diff --git a/PkmnLib.Dynamic/Models/PokemonParty.cs b/PkmnLib.Dynamic/Models/PokemonParty.cs
index 09d3cd7..23e3871 100644
--- a/PkmnLib.Dynamic/Models/PokemonParty.cs
+++ b/PkmnLib.Dynamic/Models/PokemonParty.cs
@@ -1,11 +1,12 @@
 using System.Collections;
+using PkmnLib.Static.Utils;
 
 namespace PkmnLib.Dynamic.Models;
 
 /// <summary>
 /// A collection of Pokemon.
 /// </summary>
-public interface IPokemonParty : IReadOnlyList<IPokemon?>
+public interface IPokemonParty : IReadOnlyList<IPokemon?>, IDeepCloneable
 {
     event EventHandler<(IPokemon?, int index)>? OnSwapInto;
     event EventHandler<(int index1, int index2)>? OnSwap;
diff --git a/PkmnLib.Dynamic/ScriptHandling/Script.cs b/PkmnLib.Dynamic/ScriptHandling/Script.cs
index bf51a89..c54569e 100644
--- a/PkmnLib.Dynamic/ScriptHandling/Script.cs
+++ b/PkmnLib.Dynamic/ScriptHandling/Script.cs
@@ -12,7 +12,7 @@ namespace PkmnLib.Dynamic.ScriptHandling;
 /// changes. This allows for easily defining generational differences, and add effects that the
 /// developer might require.
 /// </summary>
-public abstract class Script
+public abstract class Script : IDeepCloneable
 {
     internal event Action<Script>? OnRemoveEvent;
     
diff --git a/PkmnLib.Dynamic/ScriptHandling/ScriptContainer.cs b/PkmnLib.Dynamic/ScriptHandling/ScriptContainer.cs
index be79029..c886b60 100644
--- a/PkmnLib.Dynamic/ScriptHandling/ScriptContainer.cs
+++ b/PkmnLib.Dynamic/ScriptHandling/ScriptContainer.cs
@@ -1,5 +1,6 @@
 using System.Collections;
 using System.Diagnostics.CodeAnalysis;
+using PkmnLib.Static.Utils;
 
 namespace PkmnLib.Dynamic.ScriptHandling;
 
@@ -7,7 +8,7 @@ namespace PkmnLib.Dynamic.ScriptHandling;
 /// A holder class for a script. This is used so we can cache a list of these, and iterate over them, even when
 /// the underlying script changes.
 /// </summary>
-public class ScriptContainer : IEnumerable<ScriptContainer>
+public class ScriptContainer : IEnumerable<ScriptContainer>, IDeepCloneable
 {
     /// <inheritdoc cref="ScriptContainer"/>
     public ScriptContainer()
diff --git a/PkmnLib.Static/StatisticSet.cs b/PkmnLib.Static/StatisticSet.cs
index cabd135..1e69186 100644
--- a/PkmnLib.Static/StatisticSet.cs
+++ b/PkmnLib.Static/StatisticSet.cs
@@ -1,5 +1,6 @@
 using System.Collections;
 using System.Diagnostics.CodeAnalysis;
+using PkmnLib.Static.Utils;
 
 namespace PkmnLib.Static;
 
@@ -83,7 +84,7 @@ public record ImmutableStatisticSet<T>
 /// A set of statistics that can be changed.
 /// </summary>
 /// <typeparam name="T"></typeparam>
-public record StatisticSet<T> : ImmutableStatisticSet<T>, IEnumerable<T>
+public record StatisticSet<T> : ImmutableStatisticSet<T>, IEnumerable<T>, IDeepCloneable
     where T : struct
 {
     /// <inheritdoc cref="StatisticSet{T}"/>
diff --git a/PkmnLib.Static/Utils/DeepClone.cs b/PkmnLib.Static/Utils/DeepClone.cs
new file mode 100644
index 0000000..f99971d
--- /dev/null
+++ b/PkmnLib.Static/Utils/DeepClone.cs
@@ -0,0 +1,196 @@
+using System.Collections;
+using System.Linq.Expressions;
+using System.Reflection;
+using System.Runtime.Serialization;
+
+namespace PkmnLib.Static.Utils;
+
+/// <summary>
+/// Marks the type as deep cloneable. This means that when a deep clone is made, the object will be cloned recursively.
+/// Any reference types that are not marked as deep cloneable will be copied by reference, and not cloned.
+/// </summary>
+public interface IDeepCloneable;
+
+/// <summary>
+/// Handles deep cloning of objects. 
+/// </summary>
+public static class DeepCloneHandler
+{
+    /// <summary>
+    /// This will clone an object including all fields and properties, and recursively clone any reference types
+    /// that are marked as deep cloneable. Value types will be copied by value, and reference types that are not marked as
+    /// deep cloneable will be copied by reference.
+    ///
+    /// Recursive references will be handled correctly, and will only be cloned once, to prevent infinite loops and invalid
+    /// references.
+    /// </summary>
+    public static T DeepClone<T>(this T? obj, Dictionary<(Type, int), object>? objects = null) where T : IDeepCloneable
+    {
+        if (obj == null)
+            return default!;
+        if (objects != null && objects.TryGetValue((obj.GetType(), obj.GetHashCode()), out var value))
+            return (T)value;
+
+        var type = obj.GetType();
+        // We use GetUninitializedObject to create an object without calling the constructor. This is necessary to prevent
+        // side effects from the constructor, and to not require a parameterless constructor.
+        var newObj = FormatterServices.GetUninitializedObject(type)!;
+        
+        // If the objects dictionary is null, we create a new one. We use this dictionary to keep track of objects that have
+        // already been cloned, so we can re-use them instead of cloning them again. This is necessary to prevent infinite
+        // loops and invalid references.
+        objects ??= new Dictionary<(Type, int), object>();
+        objects.Add((obj.GetType(), obj.GetHashCode()), newObj);
+
+        var expressions = GetDeepCloneExpressions(type);
+        foreach (var (getter, setter) in expressions)
+        {
+            var v = getter.Invoke(obj);
+            if (v == null)
+                continue;
+            var cloned = DeepCloneInternal(v, v.GetType(), objects);
+            setter.Invoke(newObj, cloned);
+        }
+
+        return (T)newObj;
+    }
+
+    private static object DeepCloneInternal(object? obj, Type type, Dictionary<(Type, int), object> objects)
+    {
+        if (obj == null)
+            return null!;
+        // If the object is a value type or a string, we can just return it.
+        if (type.IsValueType || type == typeof(string))
+            return obj;
+        
+        // If the object is marked as deep cloneable, we will clone it.
+        if (type.GetInterface(nameof(IDeepCloneable)) != null)
+        {
+            // If the object is already cloned, we return the cloned object to prevent infinite loops and invalid references.
+            if (objects.TryGetValue((obj.GetType(), obj.GetHashCode()), out var value))
+                return value;
+            var o = DeepClone((IDeepCloneable)obj, objects);
+            return o;
+        }
+
+        if (type.IsArray)
+        {
+            // ReSharper disable once SuspiciousTypeConversion.Global
+            var array = (Array)obj;
+            var newArray = Array.CreateInstance(type.GetElementType()!, array.Length);
+            for (var i = 0; i < array.Length; i++)
+                newArray.SetValue(DeepCloneInternal(array.GetValue(i), type.GetElementType()!, objects),
+                    i);
+            return newArray;
+        }
+
+        if (type.IsGenericType)
+        {
+            var genericType = type.GetGenericTypeDefinition();
+            if (genericType == typeof(List<>))
+            {
+                // ReSharper disable once SuspiciousTypeConversion.Global
+                var list = (IList)obj;
+                var newList = (IList)Activator.CreateInstance(type);
+                foreach (var item in list)
+                    newList.Add(DeepCloneInternal(item, type.GetGenericArguments()[0], objects));
+                return newList;
+            }
+
+            if (genericType == typeof(Dictionary<,>))
+            {
+                // ReSharper disable once SuspiciousTypeConversion.Global
+                var dictionary = (IDictionary)obj;
+                var newDictionary = (IDictionary)Activator.CreateInstance(type);
+                foreach (DictionaryEntry entry in dictionary)
+                    newDictionary.Add(
+                        DeepCloneInternal(entry.Key, type.GetGenericArguments()[0], objects),
+                        DeepCloneInternal(entry.Value, type.GetGenericArguments()[1], objects));
+                return newDictionary;
+            }
+        }
+
+        return obj;
+    }
+
+    /// <summary>
+    /// Helper method to get the compiled expressions for deep cloning a type. This will create a getter and setter for each field
+    /// in the type, which can be used to clone the object.
+    /// </summary>
+    /// <remarks>
+    /// This method is thread safe, and will only create the expressions once for each type. It returns compiled expressions for
+    /// each field in the type, so that we can get high performance deep cloning.
+    /// </remarks>
+    private static (Func<object, object> getter, Action<object, object> setter)[]
+        GetDeepCloneExpressions(Type type)
+    {
+        // We use a lock here to prevent multiple threads from trying to create the expressions at the same time.
+        lock (DeepCloneExpressions)
+        {
+            if (DeepCloneExpressions.TryGetValue(type, out var value))
+                return value;
+
+            var fields = GetFields(type).ToArray();
+            var expressions = new (Func<object, object> getter, Action<object, object> setter)[fields.Length];
+            for (var i = 0; i < fields.Length; i++)
+            {
+                var field = fields[i];
+                // Create a compiled getter for the field.
+                // 1. Set up the instance parameter.
+                var obj = Expression.Parameter(typeof(object));
+                // 2. Cast the instance (which we want to pass as an object) to the correct type.
+                var cast = Expression.Convert(obj, type);
+                // 3. Get the field value from the instance.
+                var get = Expression.Field(cast, field);
+                // 4. Cast the field value to an object.
+                var getCasted = Expression.Convert(get, typeof(object));
+                // 5. Wrap the cast in a lambda so we can compile it.
+                var lambda = Expression.Lambda<Func<object, object>>(getCasted, obj);
+
+                // This is a slight hack to allow us to set readonly fields. We can't set them directly through expression trees,
+                // as Expression.Assign checks for this. We can however set them through reflection, so we create a setter that
+                // does this. This is not ideal as it is slower, but works for now.
+                if (field.IsInitOnly)
+                {
+                    void Setter(object instance, object v)
+                    {
+                        field.SetValue(instance, v);
+                    }
+
+                    expressions[i] = (getter: lambda.Compile(), Setter);
+                }
+                else
+                {
+                    // Create a compiled setter for the field.
+                    // 1. Set up the parameter for the value.
+                    var valueLambda = Expression.Parameter(typeof(object));
+                    // 2. Cast the value to the correct type.
+                    var valueCast = Expression.Convert(valueLambda, field.FieldType);
+                    // 3. Assign the value to the field.
+                    var assign = Expression.Assign(Expression.Field(cast, field), valueCast);
+                    // 4. Wrap the assign in a lambda so we can compile it.
+                    var set = Expression.Lambda<Action<object, object>>(assign, obj, valueLambda);
+                    expressions[i] = (getter: lambda.Compile(), setter: set.Compile());
+                }
+            }
+
+            DeepCloneExpressions.Add(type, expressions);
+            return expressions;
+        }
+    }
+
+    private static IEnumerable<FieldInfo> GetFields(Type type)
+    {
+        IEnumerable<FieldInfo> fields = type.GetFields(BindingFlags.Public | BindingFlags.Instance |
+                                                       BindingFlags.NonPublic | BindingFlags.DeclaredOnly);
+        // Note that we do the above with DeclaredOnly, while we do want to get the fields from the base type.
+        // This is because even without DeclaredOnly, we will only get public fields from our base type. As we want
+        // to get all fields, we need to do this recursively.
+        if (type.BaseType != null)
+            fields = fields.Concat(GetFields(type.BaseType));
+        return fields;
+    }
+
+    private static readonly Dictionary<Type, (Func<object, object> getter, Action<object, object> setter)[]>
+        DeepCloneExpressions = new();
+}
\ No newline at end of file
diff --git a/PkmnLib.Tests/Static/DeepCloneTests.cs b/PkmnLib.Tests/Static/DeepCloneTests.cs
new file mode 100644
index 0000000..7827e5a
--- /dev/null
+++ b/PkmnLib.Tests/Static/DeepCloneTests.cs
@@ -0,0 +1,140 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Reflection;
+using PkmnLib.Dynamic.Models;
+using PkmnLib.Static;
+using PkmnLib.Static.Species;
+using PkmnLib.Static.Utils;
+using PkmnLib.Tests.Integration;
+
+namespace PkmnLib.Tests.Static;
+
+public class DeepCloneTests
+{
+    [SuppressMessage("ReSharper", "UnusedMember.Local")]
+    [SuppressMessage("ReSharper", "ValueParameterNotUsed")]
+    private class TestClass : IDeepCloneable
+    {
+        public int Value { get; set; }
+        public int Field;
+        private int PrivateValue { get; set; }
+#pragma warning disable CS0169 // Field is never used
+        private int _privateField;
+#pragma warning restore CS0169 // Field is never used
+        private int OnlyGetter => 0;
+
+        private int OnlySetter
+        {
+            set { }
+        }
+
+        public TestClass? Self { get; set; }
+    }
+
+    [Test]
+    public async Task DeepCloneTestProperty()
+    {
+        var obj = new TestClass { Value = 1 };
+        var clone = obj.DeepClone();
+        await Assert.That(clone).IsNotEqualTo(obj);
+        await Assert.That(clone.Value).IsEqualTo(1);
+    }
+
+    [Test]
+    public async Task DeepCloneTestField()
+    {
+        var obj = new TestClass { Field = 1 };
+        var clone = obj.DeepClone();
+        await Assert.That(clone).IsNotEqualTo(obj);
+        await Assert.That(clone.Field).IsEqualTo(1);
+    }
+
+    [Test]
+    public async Task DeepCloneTestPrivateProperty()
+    {
+        var obj = new TestClass();
+        obj.GetType().GetProperty("PrivateValue", BindingFlags.NonPublic | BindingFlags.Instance)!.SetValue(obj, 1);
+        var clone = obj.DeepClone();
+        await Assert.That(clone).IsNotEqualTo(obj);
+        var clonePrivateValue =
+            clone.GetType().GetProperty("PrivateValue", BindingFlags.NonPublic | BindingFlags.Instance)!
+                .GetValue(clone);
+        await Assert.That(clonePrivateValue).IsEqualTo(1);
+    }
+
+    [Test]
+    public async Task DeepCloneTestPrivateField()
+    {
+        var obj = new TestClass();
+        obj.GetType().GetField("_privateField", BindingFlags.NonPublic | BindingFlags.Instance)!.SetValue(obj, 1);
+        var clone = obj.DeepClone();
+        await Assert.That(clone).IsNotEqualTo(obj);
+        var clonePrivateField =
+            clone.GetType().GetField("_privateField", BindingFlags.NonPublic | BindingFlags.Instance)!
+                .GetValue(clone);
+        await Assert.That(clonePrivateField).IsEqualTo(1);
+    }
+
+    [Test]
+    public async Task DeepCloneTestRecursion()
+    {
+        var obj = new TestClass();
+        obj.Self = obj;
+        var clone = obj.DeepClone();
+        await Assert.That(clone).IsNotEqualTo(obj);
+        await Assert.That(clone.Self).IsNotEqualTo(obj);
+        await Assert.That(clone.Self).IsEqualTo(clone);
+    }
+
+    [Test]
+    public async Task DeepCloneIntegrationTestsBattle()
+    {
+        var library = LibraryHelpers.LoadLibrary();
+        await Assert.That(library.StaticLibrary.Species.TryGet("bulbasaur", out var bulbasaur)).IsTrue();
+        await Assert.That(library.StaticLibrary.Species.TryGet("charmander", out var charmander)).IsTrue();
+        var party1 = new PokemonParty(6);
+        party1.SwapInto(new PokemonImpl(library, bulbasaur!,
+            bulbasaur!.GetDefaultForm(), new AbilityIndex
+            {
+                IsHidden = false,
+                Index = 0,
+            }, 50, 0,
+            Gender.Male, 0, "hardy"), 0);
+        var party2 = new PokemonParty(6);
+        party2.SwapInto(new PokemonImpl(library, charmander!,
+            charmander!.GetDefaultForm(), new AbilityIndex
+            {
+                IsHidden = false,
+                Index = 0,
+            }, 50, 0,
+            Gender.Male, 0, "hardy"), 0);
+
+        var parties = new[]
+        {
+            new BattlePartyImpl(party1, [new ResponsibleIndex(0, 0)]),
+            new BattlePartyImpl(party2, [new ResponsibleIndex(1, 0)]),
+        };
+        var battle = new BattleImpl(library, parties, false, 2, 3, randomSeed: 0);
+        battle.Sides[0].SwapPokemon(0, party1[0]);
+        battle.Sides[1].SwapPokemon(0, party2[0]);
+        party1[0]!.ChangeStatBoost(Statistic.Defense, 2, true);
+        await Assert.That(party1[0]!.StatBoost.Defense).IsEqualTo((sbyte)2);
+
+        var clone = battle.DeepClone();
+        await Assert.That(clone).IsNotEqualTo(battle);
+        await Assert.That(clone.Sides[0].Pokemon[0]).IsNotEqualTo(battle.Sides[0].Pokemon[0]);
+        await Assert.That(clone.Sides[1].Pokemon[0]).IsNotEqualTo(battle.Sides[1].Pokemon[0]);
+        
+        await Assert.That(clone.Sides[0].Pokemon[0]!.Species).IsEqualTo(battle.Sides[0].Pokemon[0]!.Species);
+        await Assert.That(clone.Sides[1].Pokemon[0]!.Species).IsEqualTo(battle.Sides[1].Pokemon[0]!.Species);
+
+        await Assert.That(clone.Library).IsEqualTo(battle.Library);
+
+        var pokemon = clone.Sides[0].Pokemon[0]!;
+        await Assert.That(pokemon.BattleData).IsNotNull();
+        await Assert.That(pokemon.BattleData).IsNotEqualTo(battle.Sides[0].Pokemon[0]!.BattleData);
+        await Assert.That(pokemon.BattleData!.Battle).IsEqualTo(clone);
+        await Assert.That(pokemon.BattleData!.SeenOpponents).Contains(clone.Sides[1].Pokemon[0]!);
+        await Assert.That(pokemon.BattleData!.SeenOpponents).DoesNotContain(battle.Sides[1].Pokemon[0]!);
+        await Assert.That(pokemon.StatBoost.Defense).IsEqualTo((sbyte)2);
+    }
+}
\ No newline at end of file