public void A() { var config = new TypeFormatter(); config .SetUpFormat <DateTime>(x => x.ToString("dd-MMM-yyyy")) .SetUpFormat <decimal>(x => x.ToString("F4")); var values = new object[] { new DateTime(2013, 11, 23), 23.4565473m, 23, "abc" }; var text = GetString( (csvWriter, objWriter) => { objWriter.WriteRow(values); }, config); Assert.AreEqual("23-Nov-2013,23.4565,23,abc", text); }