Thanks for the help Bob. I'll rewrite my unit test in that way.
I'm still curious about my mock object question. I did find that I could
create an alternate com.vividsolutions.jump.workbench.ui package in my
Eclipse project for the unit tests. I think this would only become a problem
if I wanted to reference classes or interfaces from the real
com.vividsolutions.jump.workbench.ui package in the project.
I'll explore this topic further. I may post a question on the JUnit mailing
list and report back with my findings.
The Sunburned Surveyor
On 5/3/07, Robert F. Littlefield <[EMAIL PROTECTED]> wrote:
Just pass in null for the panel parameter.
LayerRenderer lr = new LayerRenderer(null, null);
will return you a LayerRenderer object.
On 5/3/07, Sunburned Surveyor <[EMAIL PROTECTED]> wrote:
> I'm trying to cook up a mock object for the LayerViewPanel class, which
> will allow me to test elements of OpenJUMP's rendering system. However, I've
> never had a lot of experience writing or using mock objects in unit testing,
> and I have run into a couple of challenges. I was hoping I could explain my
> situation and then get some help from the other developers.
>
> I'm trying to test one of my RendererFactoryTool implementations, which
> basically creates an instance of
> com.vividsolutions.workbench.ui.renderer.LayerRenderer wjhen asked by
> the RendererFactory. (This is done whenever an instance of
> com.vividsolutions.workbench.model.Layer needs to be rendered for the
> first time.) The LayerRenderer class requires a LayerViewPanel as one of the
> arguments to its constructor. (This makes sense. The renderer needs a
> reference to an object that it can paint on.)
>
> When I am unit testing I don't want to pass the LayerRenderer
> constructor a real LayerViewPanel, because that means that I have to create
> all types of other unnecessary objects for my test. I just want to pass the
> constructor a "dumb" LayerViewPanel and see if it gives me back a Renderer.
> I need a mock object.
>
> I thought I could do this by simply extending the LayerViewPanel class
> and overriding the methods. This presents two problems:
>
> [1] To have a truly dumb object for my test I'd also need to override
> the methods of all the classes in the LayerViewPanel's inheritance tree. (Do
> you know how many methods JComponent has???) :[
>
> [2] I still have to make a call to super() in the constructor of my mock
> object class, which means I've come full circle to the original problem I
> was trying to avoid: Calling the constructor of the LayerViewPanel.
>
> the LayerViewPanel class ins't an interface, so I can't just implement
> its methods in my mock object class. What is the solution? Do I set up an
> alternate com.vividsolutions.workbench.ui package in my unit testing
> project in Eclipse and provide my own version of the LayerViewPanel class?
> (I think this will work if I don't make any other imports in my project from
> which I want to use the real com.vividsolutions.workbench.ui package.)
>
> Is there another, more elegant solution?
>
> Thanks in advance for the help. I'm really scratching my head on this
> one.
>
> The Sunburned Surveyor
>
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