I had an issue with a class that I've not encountered before with projects on which I use jMock: I have a mocked class whose method modifies an object it takes as a parameter. I suspect this is due to poor coupling in the application, but I'll refactor at a later date -- for now I welcome the challenge as an opportunity to explore three aspects of jMock with which I'm unfamiliar: custom actions, doAll and onConsecutiveCalls.
Problem
public class WillBeMocked {
public Object processBusinessObject businessObject) {
ReturnObject returnObject = new ReturnObject(businessObject);
// change state of input parameter
businessObject.incrementCounter();
return returnObject;
}
}
Solution
create custom jmock.org.api.Action in my test class
private static class BusinessObjectIncrementCounterAction<T> implements org.jmock.api.Action
{
private final BusinessObject businessObjectInstance;
public BusinessObjectIncrementCounterAction(final BusinessObject businessObjectInstance)
{
this. businessObjectInstance = businessObjectInstance;
}
@Override
public void describeTo(final Description description)
{
description.appendText("calls incrementCounter() on the businessObjectInstance");
}
@Override
public Object invoke(final Invocation invocation) throws Throwable
{
businessObjectInstance.incrementCounter();
return null;
}
}
create static call to construct custom Action in my test class
private static <T> org.jmock.api.Action incrementCounter(final BusinessObject businessObjectInstance)
{
return new BusinessObjectIncrementCounterAction <T>(businessObjectInstance);
}
use doAll to execute custom Action and mocked class's method call
context.checking(new Expectations() {
{
oneOf(willBeMockedInstance).process(businessObjectInstance);
will(doAll(incrementCounter(businessObjectInstance),
returnValue(new ReturnObject("A"))));
}
});
use onConsecutiveCall to
context.checking(new Expectations() {
{
exactly(2).of(willBeMockedInstance).process(businessObjectInstance);
will(onConsecutiveCalls(doAll(incrementCounter(businessObjectInstance),
returnValue(new ReturnObject("A")))),
doAll(incrementCounter(businessObjectInstance),
returnValue(new ReturnObject("B")))));
}
});
