public void InsertSheetTest() { MemoryStream stream = SpreadsheetReader.Create(); SpreadsheetDocument doc = SpreadsheetDocument.Open(stream, true); var worksheetPart = SpreadsheetWriter.InsertWorksheet(doc); Assert.IsNotNull(worksheetPart, "A worksheet part was not returned."); WorksheetWriter writer = new WorksheetWriter(doc, worksheetPart); writer.PasteText("B2", "Hello World"); //Save to the memory stream, and then to a file SpreadsheetWriter.Save(doc); SpreadsheetWriter.StreamToFile(string.Format("{0}\\createsheet.xlsx", GetOutputFolder()), stream); }