public void LogDoorUnlocked_SaveID111_fileHasSavedID111() { File.WriteAllText(System.AppDomain.CurrentDomain.BaseDirectory + "\\Log.txt", String.Empty); var uut = new Logfile(); var id = "222"; uut.LogDoorUnlocked(222); var fileText = File.ReadAllText(System.AppDomain.CurrentDomain.BaseDirectory + "\\Log.txt"); StringAssert.Contains(id, fileText); }