FluentAssertionsを使用してコンバータがタイプに適用されているかどうかをアサートする方法

以下のようにIMapperに拡張メソッドを作成しました。

public static AutoMapperTypeConverterAssertions<TDestinationModel>ForType<TDestinationModel>(this IMapper subject)
{
  return new AutoMapperTypeConverterAssertions<TDestinationModel>(subject);
}

public class AutoMapperTypeConverterAssertions<TDestinationModel> : ReferenceTypeAssertions<object, AutoMapperTypeConverterAssertions<TDestinationModel>>
{
   public AutoMapperTypeConverterAssertions(object subject)
   {            
     Subject = subject;
   }

   protected override string Context => "auto mapper type converter";

   public AndConstraint<AutoMapperTypeConverterAssertions<TDestinationModel>> ShouldHaveTypeConverterApplied<TSourceModel, TConverterType>(
    string because = "", params object[] becauseArgs)
   {            
      var mapper = Subject as IMapper;
      var foundTypeInConfig = mapper
        .ConfigurationProvider
        .FindTypeMapFor<TSourceModel, TDestinationModel>()
        .TypeConverterType;

      Execute.Assertion
         .BecauseOf(because, becauseArgs)
         .ForCondition(foundTypeInConfig == typeof(TConverterType))
         .FailWith("Expected the mapping for {0} to contain {1} AutoMapper   Type Converter, but was not found.", typeof(TDestinationModel).Name,   typeof(TConverterType).Name);

  }
return new     AndConstraint<AutoMapperTypeConverterAssertions<TDestinationModel>>(this);


}