我没有太多的单元测试经验。从我学到的知识来看，代码应该是解耦的，我不应该努力测试私有代码，只测试公共方法、setter 等。
现在，我已经掌握了一些基本的测试概念，但是我在将更高级的东西应用到这个案例中时遇到了麻烦......依赖注入、控制反转、模拟对象等 - 还不能理解它:(
在我继续编写代码之前，这里有一些问题。
- 在给定的课程中，我究竟应该尝试测试什么？
- 我怎样才能完成这些测试任务？
- 类设计是否存在严重问题，导致无法正确完成测试（或者即使在测试环境之外也存在明显错误）？
- 一般而言，哪些设计模式对测试网络代码有用？
另外，我一直在尝试遵守“先编写测试，然后编写代码以使测试通过”，这就是为什么我编写了前两个测试来简单地实例化类并运行它，但是当服务器能够启动并接受数据包时，我不知道接下来要测试什么...
好的，这里是代码片段。（注意：原始代码被分成几个命名空间，这就是为什么它可能看起来有点乱）
using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Threading;
namespace MyProject1
{
/// <summary>
/// Packet buffer that is sent to/received from connection
/// </summary>
public class UDPPacketBuffer
{
/// <summary>
/// Buffer size constant
/// </summary>
public const int BUFFER_SIZE = 4096;
private byte[] _data;
/// <summary>
/// Byte array with buffered data
///
/// DataLength is automatically updated when Data is set
/// </summary>
/// <see cref="DataLength"/>
public byte[] Data { get { return _data; } set { _data = value; DataLength = value.Length; } }
/// <summary>
/// Integer with length of buffered data
/// </summary>
public int DataLength;
/// <summary>
/// Remote end point (IP Address and Port)
/// </summary>
public EndPoint RemoteEndPoint;
/// <summary>
/// Initializes <see cref="UDPPacketBuffer"/> class
/// </summary>
public UDPPacketBuffer()
{
// initialize byte array
this.Data = new byte[BUFFER_SIZE];
// this will be filled in by the caller (eg. udpSocket.BeginReceiveFrom)
RemoteEndPoint = (EndPoint)new IPEndPoint(IPAddress.Any, 0);
}
/// <summary>
/// Returns <see cref="Data"/> as a byte array shortened to <see cref="DataLength"/> number of bytes
/// </summary>
public byte[] ByteContent
{
get
{
if (DataLength > 0)
{
byte[] content = new byte[DataLength];
for (int i = 0; i < DataLength; i++)
content[i] = Data[i];
return content;
}
else
{
return Data;
}
}
}
/// <summary>
/// Returns <see cref="ByteContent"/> converted to string
/// </summary>
public string StringContent { get { return Encoding.ASCII.GetString(ByteContent); } }
}
/// <summary>
/// UDP packet-related event arguments passed when invoking events
/// </summary>
/// <example>
/// This example shows how to use UDPPacketEventArgs class when event is invoked.
/// <code>
/// if (PacketSent != null)
/// PacketSent(this, new UDPPacketEventArgs(buffer, bytesSent));
/// </code>
/// </example>
public class UDPPacketEventArgs : EventArgs
{
/// <summary>
/// Instance of UDPPacketBuffer, holding current event-related buffer
/// </summary>
public UDPPacketBuffer buffer { get; private set; }
/// <summary>
/// Number of bytes sent to remote end point
/// </summary>
public int sent { get; private set; }
/// <summary>
/// Initializes <see cref="buffer"/> only. Used when receiving data.
/// </summary>
/// <param name="buffer">Buffer sent to or received from remote endpoint</param>
public UDPPacketEventArgs(UDPPacketBuffer buffer)
{
this.buffer = buffer;
}
/// <summary>
/// Initializes <see cref="buffer"/> and <see cref="sent"/> variables. Used when sending data.
/// </summary>
/// <param name="buffer">buffer that has been sent</param>
/// <param name="sent">number of bytes sent</param>
public UDPPacketEventArgs(UDPPacketBuffer buffer, int sent)
{
this.buffer = buffer;
this.sent = sent;
}
}
/// <summary>
/// Asynchronous UDP server
/// </summary>
public class AsyncUdp : ServerBase
{
private const int _defaultPort = 45112;
private int _udpPort;
/// <summary>
/// Port number on which server should listen
/// </summary>
public int udpPort { get { return _udpPort; } private set { _udpPort = value; } }
// should server listen for broadcasts?
private bool broadcast = false;
// server socket
private Socket udpSocket;
// the ReaderWriterLock is used solely for the purposes of shutdown (Stop()).
// since there are potentially many "reader" threads in the internal .NET IOCP
// thread pool, this is a cheaper synchronization primitive than using
// a Mutex object. This allows many UDP socket "reads" concurrently - when
// Stop() is called, it attempts to obtain a writer lock which will then
// wait until all outstanding operations are completed before shutting down.
// this avoids the problem of closing the socket with outstanding operations
// and trying to catch the inevitable ObjectDisposedException.
private ReaderWriterLock rwLock = new ReaderWriterLock();
// number of outstanding operations. This is a reference count
// which we use to ensure that the threads exit cleanly. Note that
// we need this because the threads will potentially still need to process
// data even after the socket is closed.
private int rwOperationCount = 0;
// the all important shutdownFlag. This is synchronized through the ReaderWriterLock.
private bool shutdownFlag = true;
/// <summary>
/// Returns server running state
/// </summary>
public bool IsRunning
{
get { return !shutdownFlag; }
}
/// <summary>
/// Initializes UDP server with arbitrary default port
/// </summary>
public AsyncUdp()
{
this.udpPort = _defaultPort;
}
/// <summary>
/// Initializes UDP server with specified port number
/// </summary>
/// <param name="port">Port number for server to listen on</param>
public AsyncUdp(int port)
{
this.udpPort = port;
}
/// <summary>
/// Initializes UDP server with specified port number and broadcast capability
/// </summary>
/// <param name="port">Port number for server to listen on</param>
/// <param name="broadcast">Server will have broadcasting enabled if set to true</param>
public AsyncUdp(int port, bool broadcast)
{
this.udpPort = port;
this.broadcast = broadcast;
}
/// <summary>
/// Raised when packet is received via UDP socket
/// </summary>
public event EventHandler PacketReceived;
/// <summary>
/// Raised when packet is sent via UDP socket
/// </summary>
public event EventHandler PacketSent;
/// <summary>
/// Starts UDP server
/// </summary>
public override void Start()
{
if (! IsRunning)
{
// create and bind the socket
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, udpPort);
udpSocket = new Socket(
AddressFamily.InterNetwork,
SocketType.Dgram,
ProtocolType.Udp);
udpSocket.EnableBroadcast = broadcast;
// we don't want to receive our own broadcasts, if broadcasting is enabled
if (broadcast)
udpSocket.MulticastLoopback = false;
udpSocket.Bind(ipep);
// we're not shutting down, we're starting up
shutdownFlag = false;
// kick off an async receive. The Start() method will return, the
// actual receives will occur asynchronously and will be caught in
// AsyncEndRecieve().
// I experimented with posting multiple AsyncBeginReceives() here in an attempt
// to "queue up" reads, however I found that it negatively impacted performance.
AsyncBeginReceive();
}
}
/// <summary>
/// Stops UDP server, if it is running
/// </summary>
public override void Stop()
{
if (IsRunning)
{
// wait indefinitely for a writer lock. Once this is called, the .NET runtime
// will deny any more reader locks, in effect blocking all other send/receive
// threads. Once we have the lock, we set shutdownFlag to inform the other
// threads that the socket is closed.
rwLock.AcquireWriterLock(-1);
shutdownFlag = true;
udpSocket.Close();
rwLock.ReleaseWriterLock();
// wait for any pending operations to complete on other
// threads before exiting.
while (rwOperationCount > 0)
Thread.Sleep(1);
}
}
/// <summary>
/// Dispose handler for UDP server. Stops the server first if it is still running
/// </summary>
public override void Dispose()
{
if (IsRunning == true)
this.Stop();
}
private void AsyncBeginReceive()
{
// this method actually kicks off the async read on the socket.
// we aquire a reader lock here to ensure that no other thread
// is trying to set shutdownFlag and close the socket.
rwLock.AcquireReaderLock(-1);
if (!shutdownFlag)
{
// increment the count of pending operations
Interlocked.Increment(ref rwOperationCount);
// allocate a packet buffer
UDPPacketBuffer buf = new UDPPacketBuffer();
try
{
// kick off an async read
udpSocket.BeginReceiveFrom(
buf.Data,
0,
UDPPacketBuffer.BUFFER_SIZE,
SocketFlags.None,
ref buf.RemoteEndPoint,
new AsyncCallback(AsyncEndReceive),
buf);
}
catch (SocketException)
{
// an error occurred, therefore the operation is void. Decrement the reference count.
Interlocked.Decrement(ref rwOperationCount);
}
}
// we're done with the socket for now, release the reader lock.
rwLock.ReleaseReaderLock();
}
private void AsyncEndReceive(IAsyncResult iar)
{
// Asynchronous receive operations will complete here through the call
// to AsyncBeginReceive
// aquire a reader lock
rwLock.AcquireReaderLock(-1);
if (!shutdownFlag)
{
// start another receive - this keeps the server going!
AsyncBeginReceive();
// get the buffer that was created in AsyncBeginReceive
// this is the received data
UDPPacketBuffer buffer = (UDPPacketBuffer)iar.AsyncState;
try
{
// get the length of data actually read from the socket, store it with the
// buffer
buffer.DataLength = udpSocket.EndReceiveFrom(iar, ref buffer.RemoteEndPoint);
// this operation is now complete, decrement the reference count
Interlocked.Decrement(ref rwOperationCount);
// we're done with the socket, release the reader lock
rwLock.ReleaseReaderLock();
// run event PacketReceived(), passing the buffer that
// has just been filled from the socket read.
if (PacketReceived != null)
PacketReceived(this, new UDPPacketEventArgs(buffer));
}
catch (SocketException)
{
// an error occurred, therefore the operation is void. Decrement the reference count.
Interlocked.Decrement(ref rwOperationCount);
// we're done with the socket for now, release the reader lock.
rwLock.ReleaseReaderLock();
}
}
else
{
// nothing bad happened, but we are done with the operation
// decrement the reference count and release the reader lock
Interlocked.Decrement(ref rwOperationCount);
rwLock.ReleaseReaderLock();
}
}
/// <summary>
/// Send packet to remote end point speified in <see cref="UDPPacketBuffer"/>
/// </summary>
/// <param name="buf">Packet to send</param>
public void AsyncBeginSend(UDPPacketBuffer buf)
{
// by now you should you get the idea - no further explanation necessary
rwLock.AcquireReaderLock(-1);
if (!shutdownFlag)
{
try
{
Interlocked.Increment(ref rwOperationCount);
udpSocket.BeginSendTo(
buf.Data,
0,
buf.DataLength,
SocketFlags.None,
buf.RemoteEndPoint,
new AsyncCallback(AsyncEndSend),
buf);
}
catch (SocketException)
{
throw new NotImplementedException();
}
}
rwLock.ReleaseReaderLock();
}
private void AsyncEndSend(IAsyncResult iar)
{
// by now you should you get the idea - no further explanation necessary
rwLock.AcquireReaderLock(-1);
if (!shutdownFlag)
{
UDPPacketBuffer buffer = (UDPPacketBuffer)iar.AsyncState;
try
{
int bytesSent = udpSocket.EndSendTo(iar);
// note that in invocation of PacketSent event - we are passing the number
// of bytes sent in a separate parameter, since we can't use buffer.DataLength which
// is the number of bytes to send (or bytes received depending upon whether this
// buffer was part of a send or a receive).
if (PacketSent != null)
PacketSent(this, new UDPPacketEventArgs(buffer, bytesSent));
}
catch (SocketException)
{
throw new NotImplementedException();
}
}
Interlocked.Decrement(ref rwOperationCount);
rwLock.ReleaseReaderLock();
}
}
/// <summary>
/// Base class used for all network-oriented servers.
/// <para>Disposable. All methods are abstract, including Dispose().</para>
/// </summary>
/// <example>
/// This example shows how to inherit from ServerBase class.
/// <code>
/// public class SyncTcp : ServerBase {...}
/// </code>
/// </example>
abstract public class ServerBase : IDisposable
{
/// <summary>
/// Starts the server.
/// </summary>
abstract public void Start();
/// <summary>
/// Stops the server.
/// </summary>
abstract public void Stop();
#region IDisposable Members
/// <summary>
/// Cleans up after server.
/// <para>It usually calls Stop() if server is running.</para>
/// </summary>
public abstract void Dispose();
#endregion
}
}
“测试代码”如下。
namespace MyProject1
{
class AsyncUdpTest
{
[Fact]
public void UdpServerInstance()
{
AsyncUdp udp = new AsyncUdp();
Assert.True(udp is AsyncUdp);
udp.Dispose();
}
[Fact]
public void StartStopUdpServer()
{
using (AsyncUdp udp = new AsyncUdp(5000))
{
udp.Start();
Thread.Sleep(5000);
}
}
string udpReceiveMessageSend = "This is a test message";
byte[] udpReceiveData = new byte[4096];
bool udpReceivePacketMatches = false;
[Fact]
public void UdpServerReceive()
{
using (AsyncUdp udp = new AsyncUdp(5000))
{
udp.Start();
udp.PacketReceived += new EventHandler(delegate(object sender, EventArgs e)
{
UDPPacketEventArgs ea = e as UDPPacketEventArgs;
if (this.udpReceiveMessageSend.Equals(ea.buffer.StringContent))
{
udpReceivePacketMatches = true;
}
});
// wait 20 ms for a socket to be bound etc
Thread.Sleep(20);
UdpClient sock = new UdpClient();
IPEndPoint iep = new IPEndPoint(IPAddress.Loopback, 5000);
this.udpReceiveData = Encoding.ASCII.GetBytes(this.udpReceiveMessageSend);
sock.Send(this.udpReceiveData, this.udpReceiveData.Length, iep);
sock.Close();
// wait 20 ms for an event to fire, it should be enough
Thread.Sleep(20);
Assert.True(udpReceivePacketMatches);
}
}
}
}
注：代码为c#，测试框架xUnit
非常感谢所有花时间回答我的问题的人！