public void ConvertFromExcelTest() { var converter = new GuidConverter(); var typeConverterOptions = new TypeConverterOptions { CultureInfo = CultureInfo.CurrentCulture }; var guid = new Guid("79f1a554-babd-41a1-8caf-185250a1fc21"); Assert.AreEqual(guid, converter.ConvertFromExcel(typeConverterOptions, "79f1a554-babd-41a1-8caf-185250a1fc21")); Assert.AreEqual(guid, converter.ConvertFromExcel(typeConverterOptions, " 79f1a554-babd-41a1-8caf-185250a1fc21 ")); try { converter.ConvertFromExcel(typeConverterOptions, null); Assert.Fail(); } catch (ExcelTypeConverterException) { } }