c# - 模拟和存根 FtpWebResponse

Question

我面临以下问题，我正在尝试使用我需要的属性创建一个假的 ftp-response，但是由于 FtpWebResponse 没有构造函数，一切都崩溃了。我收到以下错误：

 AutoFixture.ObjectCreationExceptionWithPath : AutoFixture was unable to create an instance from System.Net.FtpWebResponse because creation unexpectedly failed with exception. Please refer to the inner exception to investigate the root cause of the failure.

这是我的部分代码不起作用：

     var fixture = new Fixture();
        //fixture.Customize<FtpWebResponse>(c => c.OmitAutoProperties());
        fixture.Customize<FtpWebResponse>(c => c.FromFactory(
            new MethodInvoker(
                new GreedyConstructorQuery()))
         .OmitAutoProperties());

        var response = fixture.Create<FtpWebResponse>();

        var field_0 = typeof(FtpWebResponse).GetField("<StatusCode>k__BackingField", BindingFlags.Instance | BindingFlags.NonPublic);
        field_0.SetValue(response, FtpStatusCode.CommandOK);
        var field_1 = typeof(FtpWebResponse).GetField("<ContentLength>k__BackingField", BindingFlags.Instance | BindingFlags.NonPublic);
        field_1.SetValue(response, responseStream.Length);
        var field_2 = typeof(FtpWebResponse).GetField("<ContentType>k__BackingField", BindingFlags.Instance | BindingFlags.NonPublic);
        field_2.SetValue(response, "bytes");

        var field_3 = typeof(FtpWebResponse).GetMethod("GetStream");
        field_3.Invoke(responseStream, null);

        var client = Substitute.For<IFtpClient>();
        client.GetAsync(new Uri(_url)).ReturnsForAnyArgs(response);

任何意见，将不胜感激 ：）