I'm using Moq & NUnit as a unit test framework.
I've written a method that is given a NetworkStream object as a parameter:
public static void ReadDataIntoBuffer(NetworkStream networkStream, Queue dataBuffer)
{
if ((networkStream != null) && (dataBuffer != null))
{
while (networkStream.DataAvailable)
{
byte[] tempBuffer = new byte[512];
// read the data from the network stream into the temporary buffer
Int32 numberOfBytesRead = networkStream.Read(tempBuffer, 0, 512);
// move all data into the main buffer
for (Int32 i = 0; i < numberOfBytesRead; i++)
{
dataBuffer.Enqueue(tempBuffer[i]);
}
}
}
else
{
if (networkStream != null)
{
throw new ArgumentNullException("networkStream");
}
if (dataBuffer != null)
{
throw new ArgumentNullException("dataBuffer");
}
}
}
Now I am looking at re-writing my unit tests for this method since the previously written tests rely on real NetworkStream objects and are not very nice to handle.
How can I mock the NetworkStream? I'm using Moq as mentioned beforehand. Is it possible at all? If not how could I workaround this problem?
Looking forward to your feedback!
Here is the
previous solution:
public static void ReadDataIntoBuffer(Stream dataStream, Queue dataBuffer)
{
if ((networkStream != null) && (dataBuffer != null))
{
byte[] tempBuffer = new byte[512];
Int32 numberOfBytesRead = 0;
// read the data from the network stream into the temporary buffer
while ((numberOfBytesRead = dataStream.Read(tempBuffer, 0, 512) > 0)
{
// move all data into the main buffer
for (Int32 i = 0; i < numberOfBytesRead; i++)
{
dataBuffer.Enqueue(tempBuffer[i]);
}
}
}
else ...
}
UPDATE:
I've re-written my class once again. Unit testing using the previous solution went fine but the real-world application example showed me why it is NOT possible for me to use the (otherwise great) suggestion of passing a Stream
object into my method.
First off, my application relies on a constant TCP connection. If you use Stream.Read
(which is possible) and there is no data to receive it will block the execution. If you specify a timeout an exception will be thrown if no data is received. This kind of behaviour is not acceptable for the (rather simple) application I need. I just need a no-frills, constant TCP connection. Therefore having the NetworkStream.DataAvailable
property is paramount to my implementation.
The current solution:
I ended up writing an interface and a wrapper to NetworkStream. I also ended up passing the byte array for the temporary receive buffer into the method. Unit testing it now works rather well.
public static void ReadDataIntoBuffer(INetworkStream networkStream, Queue dataBuffer, byte[] tempRXBuffer)
{
if ((networkStream != null) && (dataBuffer != null) && (tempRXBuffer != null))
{
// read the data from the network stream into the temporary buffer
while(networkStream.DataAvailable)
{
Int32 numberOfBytesRead = networkStream.Read(tempRXBuffer, 0, tempRXBuffer.Length);
// move all data into the main buffer
for (Int32 i = 0; i < numberOfBytesRead; i++)
{
dataBuffer.Enqueue(tempRXBuffer[i]);
}
}
}
else ...
}
And here's the unit test that I use:
public void TestReadDataIntoBuffer()
{
var networkStreamMock = new Mock<INetworkStream>();
StringBuilder sb = new StringBuilder();
sb.Append(_testMessageConstant1);
sb.Append(_testMessageConstant2);
sb.Append(_testMessageConstant3);
sb.Append(_testMessageConstant4);
sb.Append(_testMessageConstant5);
// ARRANGE
byte[] tempRXBuffer = Encoding.UTF8.GetBytes(sb.ToString());
// return true so that the call to Read() is made
networkStreamMock.Setup(x => x.DataAvailable).Returns(true);
networkStreamMock.Setup(x => x.Read(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>())).Callback(() =>
{
// after the call to Read() re-setup the property so that we
// we exit the data reading loop again
networkStreamMock.Setup(x => x.DataAvailable).Returns(false);
}).Returns(tempRXBuffer.Length);
Queue resultQueue = new Queue();
// ACT
ReadDataIntoBuffer(networkStreamMock.Object, resultQueue, tempRXBuffer);
// ASSERT
Assert.AreEqual(Encoding.UTF8.GetBytes(sb.ToString()), resultQueue.ToArray());
}
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