mock.Setup(…).Returns(..); Not mocking

Question

I am running a WCF application and need to add some unit tests. Initially I tried JustMock, free version as this is the standard for the company I am at at the moment however the free version does not support system.linq.xml

So, I moved over to Moq and thought that this would work, however the code block below

Mock<IVersionFilter> mock = new Mock<IVersionFilter>();
var message = CreateValidGetProposalListMessage();
var returnValue = XDocument.Parse(GenerateXmlString());
mock.Setup(VersionFilter => VersionFilter.ParseMessage(message)).Returns(returnValue);

Which should mock the result of ParseMessage(...) from this call

public override bool Match(Message message)
{
     var doc = ParseMessage(message);

     var getProposalList = doc.Descendants(_xmlnsa + MethodConstants.GetProposalList).FirstOrDefault();
     if (getProposalList != null)
     {
        // code ommitted
     }
     /// Test code ommitted
}

public XDocument ParseMessage(Message message)
{
     XDocument doc = XDocument.Parse(message.ToString());
     return doc;
}

public Message CreateValidGetProposalListMessage()
{
    var p = new getProposalList
    {
        Code = "xxxx"
    };

    var message = Message.CreateMessage(MessageVersion.Soap11, "getProposalList xmlns=\"http://xxx\">", p);

    return message;
}

I cant see what I have missed and would be grateful if someone could help me progress this issue forward.

Thanks

Answer 1

The setup looks mostly ok. I suspect your problem is that setup isn't being invoked at all because of argument equality.

mock.Setup(VersionFilter => VersionFilter.ParseMessage(message)).Returns(returnValue);

This is saying that ParseMessage invoked with something that equals message will return returnValue . If Message is a class this will only work if Message implements it's own Equals method.

As mentioned in my OP comment, start with the basics. Ensure that the setup is being invoked first:

mock.Setup(VersionFilter => VersionFilter.ParseMessage(It.IsAny<Message>())).Returns(returnValue);

Once you've got that working, tune it to suit the test case. You can either implement an Equals method for the Message type (Fody would be my suggestion if you want to this), or match it another way via It.Is<Message>(message => match conditions) .

Answer 2

You have created a mock of IVersionFilter with this line

Mock<IVersionFilter> mock = new Mock<IVersionFilter>();

But I would expect to see a class that takes a IVersionFilter in its constructor. You would then do

 var myTestClass = new TestClass(mock.Object)

Then when the test class uses the functionality in IVersionFilter it uses the mocked one

Just to clarify, TestClass would be something like

public class TestClass(IVersionFilter filter)
{
     public void DoSomething()
     {
         filter.DoSomething();
     }
}