From 44be408fdc74cc4e925f18fadf7c81242730912f Mon Sep 17 00:00:00 2001
From: Tom Longhurst <30480171+thomhurst@users.noreply.github.com>
Date: Thu, 28 May 2026 18:16:32 +0100
Subject: [PATCH 1/2] perf(engine): replace Select+ToArray with manual Type[]
 build (#6043)

Drops the iterator + delegate allocations from per-test-registration
parameter-type extraction in TestRegistry and TestGenericTypeResolver.
---
 TUnit.Engine/Services/TestGenericTypeResolver.cs | 9 ++++++++-
 TUnit.Engine/Services/TestRegistry.cs            | 8 +++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/TUnit.Engine/Services/TestGenericTypeResolver.cs b/TUnit.Engine/Services/TestGenericTypeResolver.cs
index f6a5e216dc..294f3440da 100644
--- a/TUnit.Engine/Services/TestGenericTypeResolver.cs
+++ b/TUnit.Engine/Services/TestGenericTypeResolver.cs
@@ -44,11 +44,18 @@ public static TestGenericTypeResolution Resolve(TestMetadata metadata, TestBuild
         // Otherwise resolve from GenericMethodInfo if the test method is a generic definition
         else if (metadata.GenericMethodInfo != null)
         {
+            var parameters = metadata.MethodMetadata.Parameters;
+            var parameterTypes = new Type[parameters.Length];
+            for (var i = 0; i < parameters.Length; i++)
+            {
+                parameterTypes[i] = parameters[i].Type;
+            }
+
             result.ResolvedMethodGenericArguments = ResolveMethodGenericArguments(
                 metadata.MethodMetadata,
                 metadata.GenericMethodInfo,
                 testData.MethodData,
-                metadata.MethodMetadata.Parameters.Select(p => p.Type).ToArray());
+                parameterTypes);
         }
 
         return result;
diff --git a/TUnit.Engine/Services/TestRegistry.cs b/TUnit.Engine/Services/TestRegistry.cs
index f6e3984684..851598c9bd 100644
--- a/TUnit.Engine/Services/TestRegistry.cs
+++ b/TUnit.Engine/Services/TestRegistry.cs
@@ -138,7 +138,13 @@ public async Task<TestVariantInfo> CreateTestVariant(
                 nameof(methodArguments));
         }
 
-        var parameterTypes = methodMetadata.Parameters.Select(p => p.Type).ToArray();
+        var parameters = methodMetadata.Parameters;
+        var parameterTypes = new Type[parameters.Length];
+        for (var i = 0; i < parameters.Length; i++)
+        {
+            parameterTypes[i] = parameters[i].Type;
+        }
+
         var methodInfo = methodMetadata.Type.GetMethod(
             methodMetadata.Name,
             BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static,

From a4b92f3d557aac12a17e8399c633efad1c680911 Mon Sep 17 00:00:00 2001
From: Tom Longhurst <30480171+thomhurst@users.noreply.github.com>
Date: Thu, 28 May 2026 18:57:09 +0100
Subject: [PATCH 2/2] refactor: use Array.ConvertAll for parameter type
 extraction
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Addresses review feedback on #6076 — collapse the manual loop to a
single Array.ConvertAll call (same allocation profile, established repo
pattern via GenericTypeHelper).
---
 TUnit.Engine/Services/TestGenericTypeResolver.cs | 7 +------
 TUnit.Engine/Services/TestRegistry.cs            | 7 +------
 2 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/TUnit.Engine/Services/TestGenericTypeResolver.cs b/TUnit.Engine/Services/TestGenericTypeResolver.cs
index 294f3440da..358c2e5dce 100644
--- a/TUnit.Engine/Services/TestGenericTypeResolver.cs
+++ b/TUnit.Engine/Services/TestGenericTypeResolver.cs
@@ -44,12 +44,7 @@ public static TestGenericTypeResolution Resolve(TestMetadata metadata, TestBuild
         // Otherwise resolve from GenericMethodInfo if the test method is a generic definition
         else if (metadata.GenericMethodInfo != null)
         {
-            var parameters = metadata.MethodMetadata.Parameters;
-            var parameterTypes = new Type[parameters.Length];
-            for (var i = 0; i < parameters.Length; i++)
-            {
-                parameterTypes[i] = parameters[i].Type;
-            }
+            var parameterTypes = Array.ConvertAll(metadata.MethodMetadata.Parameters, p => p.Type);
 
             result.ResolvedMethodGenericArguments = ResolveMethodGenericArguments(
                 metadata.MethodMetadata,
diff --git a/TUnit.Engine/Services/TestRegistry.cs b/TUnit.Engine/Services/TestRegistry.cs
index 851598c9bd..de91c8a71c 100644
--- a/TUnit.Engine/Services/TestRegistry.cs
+++ b/TUnit.Engine/Services/TestRegistry.cs
@@ -138,12 +138,7 @@ public async Task<TestVariantInfo> CreateTestVariant(
                 nameof(methodArguments));
         }
 
-        var parameters = methodMetadata.Parameters;
-        var parameterTypes = new Type[parameters.Length];
-        for (var i = 0; i < parameters.Length; i++)
-        {
-            parameterTypes[i] = parameters[i].Type;
-        }
+        var parameterTypes = Array.ConvertAll(methodMetadata.Parameters, p => p.Type);
 
         var methodInfo = methodMetadata.Type.GetMethod(
             methodMetadata.Name,