Groovy-grails Mocking issue. Unable to Mock - unit-testing

Question

I have a service class method in my grails porject which uses a helper class to fetch the response as xml. The xml is then send out as the response of the service class method.
ServiceClass:-
class ItemService{
def getItem(Number) {
def HelperClass helper = new HelperClass()
def responseXml = helper.getMessage(Number)
return responseXml
}
}
I writing a test case for this method. In my test case, i wish to mock
def responseXml = helper.getMessage(Number)
The test case that i have written so far is:
class ItemServiceTest extends GroovyTestCase {
public final void testFindItem(){
def service = new ItemService()
def xml = "<Item><Number>123</Number></Item>"
def mockJobServiceFactory = new MockFor(HelperClass)
mockJobServiceFactory.demand.getMessage{ def str ->
return xml
}
service.getItem().HelperClass = mockJobServiceFactory.proxyInstance()
def item = service.getItem()("123")
assertNotNull(item)
}
but still, the mock does not return the xml that I speicified in the test case.
Any problems that you see in the above approach?...Advance Thanks

Answer 1

When you mock objects with MockFor, you need to surround the code that uses the mock in a use closure. Try this:
def service = new ItemService()
def xml = "<Item><Number>123</Number></Item>"
def mockJobServiceFactory = new MockFor(HelperClass)
mockJobServiceFactory.demand.getMessage{ def str ->
return xml
}
mockJobServiceFactory.use {
def item = service.getItem()("123")
assertNotNull(item)
}