Add test.

Author: teo-tsirpanis

src/libraries/System.Reflection.Metadata/tests/Metadata/TypeSystem/TypeDefinitionTests.cs

@@ -32,5 +32,41 @@ public void ValidateTypeDefinitionIsNestedWindowsProjection()
                 Assert.Equal(typeDef.Attributes.IsNested(), typeDef.IsNested);
             }
         }
+
+        [Fact]
+        public void ValidateDeclaringType()
+        {
+            var reader = MetadataReaderTests.GetMetadataReader(Misc.Members);
+
+            foreach (var typeDefHandle in reader.TypeDefinitions)
+            {
+                var typeDef = reader.GetTypeDefinition(typeDefHandle);
+                foreach (var nestedTypeHandle in typeDef.GetNestedTypes())
+                {
+                    var nestedType = reader.GetTypeDefinition(nestedTypeHandle);
+                    Assert.Equal(typeDefHandle, nestedType.GetDeclaringType());
+                }
+                foreach (var fieldHandle in typeDef.GetFields())
+                {
+                    var field = reader.GetFieldDefinition(fieldHandle);
+                    Assert.Equal(typeDefHandle, field.GetDeclaringType());
+                }
+                foreach (var methodHandle in typeDef.GetMethods())
+                {
+                    var method = reader.GetMethodDefinition(methodHandle);
+                    Assert.Equal(typeDefHandle, method.GetDeclaringType());
+                }
+                foreach (var eventHandle in typeDef.GetEvents())
+                {
+                    var eventDef = reader.GetEventDefinition(eventHandle);
+                    Assert.Equal(typeDefHandle, eventDef.GetDeclaringType());
+                }
+                foreach (var propertyHandle in typeDef.GetProperties())
+                {
+                    var property = reader.GetPropertyDefinition(propertyHandle);
+                    Assert.Equal(typeDefHandle, property.GetDeclaringType());
+                }
+            }
+        }
     }
 }