public void SetUp()
        {
            XmlDocument xmlDoc      = new XmlDocument();
            XmlElement  log4NetNode = xmlDoc.CreateElement(Log4NetXmlConstants.Log4Net);

            IElementConfiguration configuration = Substitute.For <IElementConfiguration>();

            configuration.ConfigXml.Returns(xmlDoc);
            configuration.Log4NetNode.Returns(log4NetNode);

            mSut = new MemoryAppender(configuration);
            mSut.Initialize();
        }