From db83e09d8abfc8790314f27bd79c8a7957ea7c68 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Sim=C3=B5es?= <jose.simoes@eclo.solutions>
Date: Thu, 7 May 2026 13:20:18 +0100
Subject: [PATCH 1/2] Improve test class discovery

- Test-class filtering logic moverd to shared code so class scanning now excludes Attribute-derived types before calling type-level custom-attribute reflection.
---
 source/TestAdapter/Discover.cs       |  2 +-
 source/TestFrameworkShared/Helper.cs | 27 +++++++++++++++++++++++++++
 source/UnitTestLauncher/Program.cs   |  2 +-
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/source/TestAdapter/Discover.cs b/source/TestAdapter/Discover.cs
index 143648b..927ba2b 100644
--- a/source/TestAdapter/Discover.cs
+++ b/source/TestAdapter/Discover.cs
@@ -120,7 +120,7 @@ public static List<TestCase> ComposeTestCases(string sourceFile)
             AppDomain.CurrentDomain.Load(test.GetName());
 
             var typeCandidatesForTests = test.GetTypes()
-                                            .Where(x => x.IsClass);
+                                            .Where(Helper.IsTestClassCandidate);
 
             foreach (var typeCandidate in typeCandidatesForTests)
             {
diff --git a/source/TestFrameworkShared/Helper.cs b/source/TestFrameworkShared/Helper.cs
index 5041f01..8d6192f 100644
--- a/source/TestFrameworkShared/Helper.cs
+++ b/source/TestFrameworkShared/Helper.cs
@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
+
 namespace nanoFramework.TestFramework
 {
     /// <summary>
@@ -10,6 +12,31 @@ public static class Helper
     {
         private delegate bool AnyDelegateType(object source);
 
+        /// <summary>
+        /// Checks whether a type can be considered for test discovery and execution.
+        /// </summary>
+        /// <param name="type">Type to inspect.</param>
+        /// <returns><see langword="true"/> when the type is a class and not an attribute type.</returns>
+        public static bool IsTestClassCandidate(Type type)
+        {
+            return type.IsClass && !IsAttributeType(type);
+        }
+
+        private static bool IsAttributeType(Type type)
+        {
+            var attributeFullName = typeof(Attribute).FullName;
+
+            for (var current = type; current != null; current = current.BaseType)
+            {
+                if (current.FullName == attributeFullName)
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
         private static bool Any(this object[] array, AnyDelegateType predicate)
         {
             foreach (var item in array)
diff --git a/source/UnitTestLauncher/Program.cs b/source/UnitTestLauncher/Program.cs
index b88fc50..1e6bcb2 100644
--- a/source/UnitTestLauncher/Program.cs
+++ b/source/UnitTestLauncher/Program.cs
@@ -22,7 +22,7 @@ public static void Main()
 
             foreach (var type in allTypes)
             {
-                if (!type.IsClass)
+                if (!Helper.IsTestClassCandidate(type))
                 {
                     continue;
                 }

From b154bf283ed3e4c61c3d28b7a29b2c2b518d3101 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Sim=C3=B5es?= <jose.simoes@eclo.solutions>
Date: Thu, 7 May 2026 13:53:22 +0100
Subject: [PATCH 2/2] Improvement from code review

---
 source/TestFrameworkShared/Helper.cs | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/source/TestFrameworkShared/Helper.cs b/source/TestFrameworkShared/Helper.cs
index 8d6192f..570b38c 100644
--- a/source/TestFrameworkShared/Helper.cs
+++ b/source/TestFrameworkShared/Helper.cs
@@ -26,15 +26,27 @@ private static bool IsAttributeType(Type type)
         {
             var attributeFullName = typeof(Attribute).FullName;
 
-            for (var current = type; current != null; current = current.BaseType)
+            Type current = type;
+            while (current != null)
             {
                 if (current.FullName == attributeFullName)
                 {
                     return true;
                 }
+                try
+                {
+                    current = current.BaseType;
+                }
+                catch
+                {
+                    // Base type assembly not resolvable in this reflection context;
+                    // conservatively treat as attribute to avoid calling GetCustomAttributes on it.
+                    return true;
+                }
             }
 
             return false;
+
         }
 
         private static bool Any(this object[] array, AnyDelegateType predicate)