perf: eliminate store.ToArray() allocation on mock behavior execution hot path

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Generic_Interface_Extension_Discovery.verified.txt

@@ -166,7 +166,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IRepository_string__GetById_M0_MockCall Callback(global::System.Action<int> callback)
         {
-            EnsureSetup().Callback(args => callback((int)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -236,7 +236,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IRepository_string__Save_M1_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Generic_Interface_With_Class_Type_Argument.verified.txt

@@ -149,7 +149,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public Sandbox_IFoo_Sandbox_Bar__Process_M1_MockCall Callback(global::System.Action<global::Sandbox.Bar> callback)
         {
-            EnsureSetup().Callback(args => callback((global::Sandbox.Bar)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Generic_Interface_With_Multiple_Non_Builtin_Type_Arguments.verified.txt

@@ -143,7 +143,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public Sandbox_IMapper_Sandbox_Entity_Sandbox_Status__Map_M0_MockCall Callback(global::System.Action<global::Sandbox.Entity> callback)
         {
-            EnsureSetup().Callback(args => callback((global::Sandbox.Entity)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Generic_Interface_With_Nested_Namespace_Type_Argument.verified.txt

@@ -149,7 +149,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public Sandbox_IService_Outer_Inner_Config__Apply_M1_MockCall Callback(global::System.Action<global::Outer.Inner.Config> callback)
         {
-            EnsureSetup().Callback(args => callback((global::Outer.Inner.Config)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_Inheriting_Multiple_Interfaces.verified.txt

@@ -165,7 +165,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IReadWriter_Write_M2_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_With_Async_Methods.verified.txt

@@ -260,7 +260,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IAsyncService_GetValueAsync_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -415,7 +415,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IAsyncService_ComputeAsync_M2_MockCall Callback(global::System.Action<int> callback)
         {
-            EnsureSetup().Callback(args => callback((int)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -492,7 +492,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IAsyncService_InitializeAsync_M3_MockCall Callback(global::System.Action<global::System.Threading.CancellationToken> callback)
         {
-            EnsureSetup().Callback(args => callback((global::System.Threading.CancellationToken)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_With_Events.verified.txt

@@ -195,7 +195,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public INotifier_Notify_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_With_Keyword_Parameter_Names.verified.txt

@@ -171,7 +171,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public ITest_Test_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -251,7 +251,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public ITest_Get_M1_MockCall Callback(global::System.Action<int, string> callback)
         {
-            EnsureSetup().Callback(args => callback((int)args[0]!, (string)args[1]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_With_Mixed_Members.verified.txt

@@ -274,7 +274,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IService_GetAsync_M3_MockCall Callback(global::System.Action<int> callback)
         {
-            EnsureSetup().Callback(args => callback((int)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -347,7 +347,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IService_Process_M4_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_With_Nullable_Reference_Type_Parameters.verified.txt

@@ -288,7 +288,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IFoo_Bar_M0_MockCall Callback(global::System.Action<object?> callback)
         {
-            EnsureSetup().Callback(args => callback((object?)args[0]));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -368,7 +368,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IFoo_GetValue_M1_MockCall Callback(global::System.Action<string?, int> callback)
         {
-            EnsureSetup().Callback(args => callback((string?)args[0], (int)args[1]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -438,7 +438,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IFoo_Process_M2_MockCall Callback(global::System.Action<string, string?, object?> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!, (string?)args[1], (object?)args[2]));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -530,7 +530,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IFoo_GetAsync_M3_MockCall Callback(global::System.Action<string?> callback)
         {
-            EnsureSetup().Callback(args => callback((string?)args[0]));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_With_Out_Ref_Parameters.verified.txt

@@ -172,7 +172,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IDictionary_TryGetValue_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -245,7 +245,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IDictionary_Swap_M1_MockCall Callback(global::System.Action<int, int> callback)
         {
-            EnsureSetup().Callback(args => callback((int)args[0]!, (int)args[1]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_With_Overloaded_Methods.verified.txt

@@ -265,7 +265,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IFormatter_Format_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -345,7 +345,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IFormatter_Format_M1_MockCall Callback(global::System.Action<int> callback)
         {
-            EnsureSetup().Callback(args => callback((int)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -425,7 +425,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IFormatter_Format_M2_MockCall Callback(global::System.Action<string, string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!, (string)args[1]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -505,7 +505,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IFormatter_Format_M3_MockCall Callback(global::System.Action<string, string, string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!, (string)args[1]!, (string)args[2]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_With_Static_Abstract_Transitive_Return_Type.verified.txt

@@ -162,7 +162,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IMyService_GetValue_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Multi_Method_Interface.verified.txt

@@ -209,7 +209,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public ICalculator_Add_M0_MockCall Callback(global::System.Action<int, int> callback)
         {
-            EnsureSetup().Callback(args => callback((int)args[0]!, (int)args[1]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 
@@ -289,7 +289,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public ICalculator_Subtract_M1_MockCall Callback(global::System.Action<int, int> callback)
         {
-            EnsureSetup().Callback(args => callback((int)args[0]!, (int)args[1]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Partial_Mock_Filters_Internal_Virtual_Members_From_External_Assembly.verified.txt

@@ -168,7 +168,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public ExternalLib_ExternalClient_PublicMethod_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Partial_Mock_Filters_Members_With_Internal_Signature_Types.verified.txt

@@ -128,7 +128,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public ExternalLib_ServiceClient_GetValue_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Simple_Interface_With_One_Method.verified.txt

@@ -143,7 +143,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public IGreeter_Greet_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Static_Extension_Discovery_Without_Mock_Of.verified.txt

@@ -149,7 +149,7 @@ namespace TUnit.Mocks.Generated
         /// <summary>Execute a typed callback using the actual method parameters.</summary>
         public INotifier_Notify_M0_MockCall Callback(global::System.Action<string> callback)
         {
-            EnsureSetup().Callback(args => callback((string)args[0]!));
+            EnsureSetup().Callback(callback);
             return this;
         }
 

TUnit.Mocks.SourceGenerator/Builders/MockMembersBuilder.cs

@@ -432,12 +432,22 @@ private static void GenerateTypedCallbackOverload(CodeWriter writer, List<MockPa
     {
         var typeList = string.Join(", ", nonOutParams.Select(p => p.FullyQualifiedType));
         var actionType = $"global::System.Action<{typeList}>";
-        var castArgs = BuildCastArgs(nonOutParams, allNonOutParams);
 
         writer.AppendLine("/// <summary>Execute a typed callback using the actual method parameters.</summary>");
         using (writer.Block($"public {wrapperName} Callback({actionType} callback)"))
         {
-            writer.AppendLine($"EnsureSetup().Callback(args => callback({castArgs}));");
+            // allNonOutParams is null when this is the primary overload (no out/ref struct subset remapping).
+            // In that case the callback's parameter types match the typed Callback<T1,...> overload directly,
+            // so we can register it without a wrapping closure — avoiding the object?[] allocation.
+            if (allNonOutParams is null && nonOutParams.Count <= MaxTypedParams)
+            {
+                writer.AppendLine("EnsureSetup().Callback(callback);");
+            }
+            else
+            {
+                var castArgs = BuildCastArgs(nonOutParams, allNonOutParams);
+                writer.AppendLine($"EnsureSetup().Callback(args => callback({castArgs}));");
+            }
             writer.AppendLine("return this;");
         }
     }