How to Moq a FtpDataStream

我编写了一个FTP客户端应用程序，用nunit工具测试了我的功能。我尝试模拟FTP数据流。gettallcsvfilesfromftp方法调用FtpConnect()方法，但在测试时，我想获得流数据而不连接FTP服务器。

    public List<string> GetAllCsvFilesFromFTP()
    {
        var files = new List<string>();
        var responseStream = _ftpConnection.FtpConnect(WebRequestMethods.Ftp.ListDirectory);
        if (responseStream != null)
        {
            var reader = new StreamReader(responseStream);
            ReadResponseStream(files, reader);
            reader.Close();
            responseStream.Close();
        }
        return files.OrderByDescending(p => p).ToList();
    }
    public Stream FtpConnect(string connectionType, string fileName = "")
    {
        try
        {
            var request = (FtpWebRequest)WebRequest.Create(_readConfigXml.FtpUrl + fileName);
            request.Credentials = new NetworkCredential(_readConfigXml.UserName, _readConfigXml.PassWord);
            request.UsePassive = true;
            request.UseBinary = true;
            request.KeepAlive = true;
            request.Method = connectionType;
            var response = (FtpWebResponse) request.GetResponse();
            var stream = response.GetResponseStream();
            return stream;
        }
        catch (Exception ex)
        {
            _logWriter.WriteLog(_readConfigXml.LogPath, ex.Message);
            return null;
        }
    }

我试着模拟测试的设置方法如下:_ftpConnection。设置(m => m.FtpConnect (It.IsAny (), It.IsAny ())) .Returns (?),

你能告诉我如何模拟退货数据吗?

string csvdata = "1,2,3,4,5":
var ms = new MemoryStream(Encoding.UTF8.GetBytes(csvdata));
ms.Position = 0;
_ftpConnection.Setup(m => m.FtpConnect(It.IsAny(), It.IsAny())).Returns(ms);