How to Unit test a function which sends a networkstream to a server

Question

I have implemented a simple chat program (found here: http://csharp.net-informations.com/communications/csharp-chat-server.htm), and I wish to unit test the function "button1_Click" in my client, but how would I do this? I can't figure out how to test, that the function outputs the coorect stream.

I'm fairly new to the world of unit tests, so any help is appriciated :)

The client is as follows:

using System;
using System.Windows.Forms;
using System.Text;
using System.Net.Sockets ;
using System.Threading;

namespace WindowsApplication2
{
    public partial class Form1 : Form
    {
        System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();
        NetworkStream serverStream = default(NetworkStream);
        string readData = null;

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            byte[] outStream = System.Text.Encoding.ASCII.GetBytes(textBox2.Text + "$");
            serverStream.Write(outStream, 0, outStream.Length);
            serverStream.Flush();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            readData = "Conected to Chat Server ...";
            msg();
            clientSocket.Connect("127.0.0.1", 8888);
            serverStream = clientSocket.GetStream();

            byte[] outStream = System.Text.Encoding.ASCII.GetBytes(textBox3.Text + "$");
            serverStream.Write(outStream, 0, outStream.Length);
            serverStream.Flush();

            Thread ctThread = new Thread(getMessage);
            ctThread.Start();
        }

        private void getMessage()
        {
            while (true)
            {
                serverStream = clientSocket.GetStream();
                int buffSize = 0;
                byte[] inStream = new byte[10025];
                buffSize = clientSocket.ReceiveBufferSize;
                serverStream.Read(inStream, 0, buffSize);
                string returndata = System.Text.Encoding.ASCII.GetString(inStream);
                readData = "" + returndata;
                msg();
            }
        }

        private void msg()
        {
            if (this.InvokeRequired)
                this.Invoke(new MethodInvoker(msg));
            else
                textBox1.Text = textBox1.Text + Environment.NewLine + " >> " + readData;
        } 

    }
}

and the server is as follows:

using System;
using System.Threading;
using System.Net.Sockets;
using System.Text;
using System.Collections;

namespace ConsoleApplication1
{
    class Program
    {
        public static Hashtable clientsList = new Hashtable(); 

        static void Main(string[] args)
        {
            TcpListener serverSocket = new TcpListener(8888);
            TcpClient clientSocket = default(TcpClient);
            int counter = 0;

            serverSocket.Start();
            Console.WriteLine ("Chat Server Started ....");
            counter = 0;
            while ((true))
            {
                counter += 1;
                clientSocket = serverSocket.AcceptTcpClient();

                byte[] bytesFrom = new byte[10025];
                string dataFromClient = null;

                NetworkStream networkStream = clientSocket.GetStream();
                networkStream.Read(bytesFrom, 0, (int)clientSocket.ReceiveBufferSize);
                dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
                dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));

                clientsList.Add(dataFromClient, clientSocket);

                broadcast(dataFromClient + " Joined ", dataFromClient, false);

                Console.WriteLine(dataFromClient + " Joined chat room ");
                handleClinet client = new handleClinet();
                client.startClient(clientSocket, dataFromClient, clientsList);
            }

            clientSocket.Close();
            serverSocket.Stop();
            Console.WriteLine("exit");
            Console.ReadLine();
        }

        public static  void broadcast(string msg, string uName, bool flag)
        {
            foreach (DictionaryEntry Item in clientsList)
            {
                TcpClient broadcastSocket;
                broadcastSocket = (TcpClient)Item.Value;
                NetworkStream broadcastStream = broadcastSocket.GetStream();
                Byte[] broadcastBytes = null;

                if (flag == true)
                {
                    broadcastBytes = Encoding.ASCII.GetBytes(uName + " says : " + msg);
                }
                else
                {
                    broadcastBytes = Encoding.ASCII.GetBytes(msg);
                }

                broadcastStream.Write(broadcastBytes, 0, broadcastBytes.Length);
                broadcastStream.Flush();
            }
        }  //end broadcast function
    }//end Main class


    public class handleClinet
    {
        TcpClient clientSocket;
        string clNo;
        Hashtable clientsList;

        public void startClient(TcpClient inClientSocket, string clineNo, Hashtable cList)
        {
            this.clientSocket = inClientSocket;
            this.clNo = clineNo;
            this.clientsList = cList;
            Thread ctThread = new Thread(doChat);
            ctThread.Start();
        }

        private void doChat()
        {
            int requestCount = 0;
            byte[] bytesFrom = new byte[10025];
            string dataFromClient = null;
            Byte[] sendBytes = null;
            string serverResponse = null;
            string rCount = null;
            requestCount = 0;

            while ((true))
            {
                try
                {
                    requestCount = requestCount + 1;
                    NetworkStream networkStream = clientSocket.GetStream();
                    networkStream.Read(bytesFrom, 0, (int)clientSocket.ReceiveBufferSize);
                    dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
                    dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));
                    Console.WriteLine("From client - " + clNo + " : " + dataFromClient);
                    rCount = Convert.ToString(requestCount);

                    Program.broadcast (dataFromClient, clNo, true);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
            }//end while
        }//end doChat
    } //end class handleClinet
}//end namespace