Fix MVC Core tests for CoreCLR GetCustomAttributes consistency (#62872)

Co-authored-by: Jan Kotas <[email protected]>

Author: medhatiwari

src/Mvc/Mvc.Core/test/ModelBinding/Metadata/DefaultModelMetadataProviderTest.cs

@@ -211,8 +211,14 @@ public void GetMetadataForParameter_SuppliesEmptyAttributes_WhenParameterHasNoAt
         // Assert
         var defaultMetadata = Assert.IsType<DefaultModelMetadata>(metadata);
 
-        // Not exactly "no attributes" due to SerializableAttribute on object.
-        Assert.IsType<SerializableAttribute>(Assert.Single(defaultMetadata.Attributes.Attributes));
+        // The parameter itself has no attributes
+        Assert.Empty(defaultMetadata.Attributes.ParameterAttributes);
+
+        // Type attributes exist (but we don't care what they are - that's runtime implementation detail)
+        Assert.NotEmpty(defaultMetadata.Attributes.TypeAttributes);
+
+        // Combined attributes = ParameterAttributes + TypeAttributes (when parameter has no attributes)
+        Assert.Equal(defaultMetadata.Attributes.TypeAttributes, defaultMetadata.Attributes.Attributes);
     }
 
     [Fact]

src/Mvc/Mvc.Core/test/ModelBinding/Metadata/ModelAttributesTest.cs

@@ -185,11 +185,15 @@ public void GetAttributesForParameter_NoAttributes()
                 .GetParameters()[0]);
 
         // Assert
-        // Not exactly "no attributes" due to SerializableAttribute on object.
-        Assert.IsType<SerializableAttribute>(Assert.Single(attributes.Attributes));
+        // The parameter itself has no attributes
         Assert.Empty(attributes.ParameterAttributes);
         Assert.Null(attributes.PropertyAttributes);
-        Assert.Equal(attributes.Attributes, attributes.TypeAttributes);
+
+        // Type attributes exist (but we don't care what they are - that's runtime implementation detail)
+        Assert.NotEmpty(attributes.TypeAttributes);
+
+        // Combined attributes = ParameterAttributes + TypeAttributes (when parameter has no attributes)
+        Assert.Equal(attributes.TypeAttributes, attributes.Attributes);
     }
 
     [Fact]