Mocking/Stubbing Class with Static Factory Method and Regular Methods

[Ivan Krizsan]

Hi!
Another question, again regarding testing using MockFor or StubFor:
If I want to mock/stub a class like Calendar that has a static factory method to create instances of the class and also regular methods, I don't know how to return the mock/stub from the factory method.
Here is my code so far:

import groovy.mock.interceptor.MockFor
import java.util.Calendar

class TestCalendarStaticMock extends GroovyTestCase
{       
    void testWithMockFor()
    {
        def theMock = new MockFor(Calendar)
        theMock.demand.getInstance
        {
            def theMetaMethod = theMock.proxy.getStaticMetaMethod("getInstance", null)

           /* This is not good, since it returns a new instance of Calendar, not the mock/stub. */
            theMetaMethod.invoke(delegate, null)
        }
        
        /* 
         * The first demand should really not be here (?) and the second demand will never be met, since the
         * mock/stub is not returned from the getInstance factory method so the get method will never be invoked
         * on the mock/stub, but on a real instance of Calendar.
         */
        theMock.demand.getDAY_OF_WEEK { 2 }
        //theMock.demand.get(1..1) { 3 }
        
        theMock.metaClass.static.getInstance = { null }
        
        theMock.use
        {
            def theOUT = new CalendarUser()
            def theDayOfWeek = theOUT.doCalcCurrentDayOfWeek()
            println "The day of week: $theDayOfWeek"
        }
    }
}

class CalendarUser
{
    def doCalcCurrentDayOfWeek()
    {
        Calendar theCalendar = Calendar.getInstance()
        println "Calendar: $theCalendar"
        theCalendar.get(Calendar.DAY_OF_WEEK)
    }
}

Many thanks in advance!