unti testint LoadState

[anisha.silva]

ho how do i write unit test for the blow method

public static void LoadState()
        {
        XmlTextReader
            TextFile = null;

        // program state file exist
        if(File.Exists(FileName))
            {
            try
                {
                // read program state file
                TextFile = new XmlTextReader(FileName);

                // create xml serializing object
                XmlSerializer XmlFile = new XmlSerializer(typeof(ProgramState));

                // deserialize the program state
                State = (ProgramState) XmlFile.Deserialize(TextFile);
                }
            catch
                {
                State = null;
                }

            // close the file
            if(TextFile != null) TextFile.Close();
            }

        // we have no program state file
        if(State == null)
            {
            // create new default program state
            State = new ProgramState();

            // save default
            SaveState();
            }

        // exit
        return;
        }

can someone give me how to start because there is no return valur to create assert.areEqual, how do i test this

appreciate a reply
thanks