RE: [MO-java-users] Making Mock Objects for Static Members

[Ilja P. <pr...@di...>]

moc...@li... wrote:
> Subject: [MO-java-users] Making Mock Objects for Static Members
> 
> 
> Hi,
> 
> I have a class that I want to test but I'm having trouble
> creating MockObjects for the classes referenced by my class. Consider
> the code below: 
> 
> public class MyClassToTest
> {
>    private ClassA a = ClassAFactory().instance().getGlobalClassA()
> 
>    public MyClassToTest()
>    {   }
> 
>    public myMethodToTest()
>    {
>       ClassB classBInst = new ClassB();
>    }
> }
> 
> I want to mock ClassA and ClassB. ClassA internally accesses
> a database and ClassB makes a JNDI lookup and both classes
> read configuration info from a properties file. Actually most
> of my classes read config from properties files using something like:
>     private static final Properties PROPERTIES =
> PropertiesLoader.load(PROPERTIES_FILE_NAME);
> This is another thing that I want to mock.
> 
> But how do I get the Mocks for ClassA and ClassB to
> MyClassToTest? The only way to do it seems to me to pass
> instances of ClassA and ClassB to the class constructor and
> to the method as parameters. But this changes the public
> interface of my class and I don't want the clients of this
> class to be burdened with the details of creating ClassA and
> ClassB. So how can I effectively test MyClassToTest?

For ClassA, you could make the ClassAFactory configurable. The test
would configure it so that instance() returns a mock implementation.
(That's what factories are for, aren't they???)

For ClassB, you could enhance the interface by a myMethodToTest(ClassB),
and the method without the parameter could simly delegate to it (so that
it's dumb enough to not need testing at all).

Does that help?