Add assertion for DeclaringType in TypeExtensionsTests

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Author: koenbeuk

tests/ExpressiveSharp.Tests/Extensions/TypeExtensionsTests.cs

@@ -131,5 +131,6 @@ public void GetConcreteProperty_InterfacePropertyWithNonPublicAccessor_DoesNotTh
         var result = typeof(HiddenImpl).GetConcreteProperty(interfaceProperty);
 
         Assert.IsNotNull(result);
+        Assert.AreEqual(typeof(HiddenImpl), result.DeclaringType);
     }
 }