Question

I’m unit testing a demo application, which is a POP3 client. The POP3 client implements IDisposable, so I’m trying to test a using cycle.

(I’m using nunit 2.5.2 and Moq 4.0)

/// <summary>
/// Unsuccessful construct dispose cycle, no ILogger object given. 
/// Expecting ArgumentNullException. Expecting TcpClient dispose to be called.
/// </summary>
[Test]
[ExpectedException(typeof(ArgumentNullException))]
public void ConstructorDispose_LoggerNull_ArgumentNullException()
{
    mockTcpClient.Setup(x => x.Dispose());
    using (var popClient = new PopClient(null, mockTcpClient.Object))
    {

    }
    mockTcpClient.VerifyAll();
}

As you can see the verifyAll method will never be invoked and the test will be successful, nonetheless. So …

• What is the best way to solve this?
• Is there another way then try catch?

Update I fixed it like this for the moment:

        mockTcpClient.Setup(x => x.Dispose());
        var correctExceptionThrown = false;
        try
        {
            using (var popClient = new PopClient(null, mockTcpClient.Object))
            {

            }
        }
        catch (ArgumentNullException)
        {
            correctExceptionThrown = true;
        }
        finally
        {
            mockTcpClient.VerifyAll();
        }
        Assert.That(correctExceptionThrown);

But dispose isn’t called, seems to be the C# specification.

Answer 1

mockTcpClient.Setup(x => x.Dispose());

try 
{
    using (var popClient = new PopClient(null, mockTcpClient.Object))
    {

    }
}
finally 
{
    mockTcpClient.VerifyAll();
}