Fix deployment regression

Author: Youssef1313

src/Adapter/MSTestAdapter.PlatformServices/Extensions/TestCaseExtensions.cs

@@ -72,7 +72,15 @@ internal static UnitTestElement ToUnitTestElement(this TestCase testCase, string
     {
         if (testCase.LocalExtensionData is UnitTestElement unitTestElement)
         {
-            return unitTestElement;
+            // If the requested source is different, clone it with updated source.
+            // This can happen when there are deployment items in tests.
+            // In this case, the source would be the path of the deployment directory.
+            // If we don't return UnitTestElement with the correct path to deployment directory, we will
+            // end up trying to load the test assembly twice in the same appdomain, once with the default context and once in a LoadFrom context.
+            // See https://github.com/microsoft/testfx/issues/6713
+            return unitTestElement.TestMethod.AssemblyName != source
+                ? unitTestElement.CloneWithUpdatedSource(source)
+                : unitTestElement;
         }
 
         string? testClassName = testCase.GetPropertyValue(EngineConstants.TestClassNameProperty) as string;

src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/TestMethod.cs

@@ -165,4 +165,11 @@ public string? DeclaringClassFullName
     internal string DisplayName { get; set; }
 
     internal TestMethod Clone() => (TestMethod)MemberwiseClone();
+
+    internal TestMethod CloneWithUpdatedSource(string source)
+    {
+        var clone = (TestMethod)MemberwiseClone();
+        AssemblyName = source;
+        return clone;
+    }
 }

src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/UnitTestElement.cs

@@ -92,6 +92,13 @@ internal UnitTestElement Clone()
         return clone;
     }
 
+    internal UnitTestElement CloneWithUpdatedSource(string source)
+    {
+        var clone = (UnitTestElement)MemberwiseClone();
+        clone.TestMethod = TestMethod.CloneWithUpdatedSource(source);
+        return clone;
+    }
+
     /// <summary>
     /// Convert the UnitTestElement instance to an Object Model testCase instance.
     /// </summary>