jmockit - Mocking chain of methods one of which returns a Collection using #Cascading - jmockit

Question

I am trying to mock a method call which goes something like this:
rapContext.getSysInfo().get(key)
The getSysInfo() method returns a ConcurrentHashMap.
Here is what I have done:
Class ABCTest {
#Cascading RapContext context;
#Test
doTest() {
new Expectations() {
{
rapContext.getSysInfo().get(anyString);
result = new UserPrefCtxObject();
}
}
}
With this I get a NullPointerException on rapContext.getSysInfo(). Call to getSysInfo() returns null. If I call any other method which does not return a collection, for instance rapContext.getDomain() everything working fine.
I am not sure what I am missing.
Thanks

Answer 1

The code example is not complete however you are likely running into some issue associated with accidentally mocking Map. If a Map (or any part of the Collection framework) is mocked then a lot of things will break. I could not reproduce your problem as any attempt to mock RapContext using #Cascading resulted in a stack over flow.
You could partially mock RapContext instead and then either return a real or mocked Map. When I run into similar issues I generally get around them using either #Injectable to only mock an instance of a class or using partial mocks.
Here is an approach that will let you mock getSysInfo:
public class RapContextTest {
#Injectable ConcurrentHashMap<String, Object> mockedMap;
#Test
public void testContext() {
RapContext context = new RapContext();
new MockUp<RapContext>(){
#Mock
public ConcurrentHashMap getSysInfo(){
return mockedMap;
}
};
new NonStrictExpectations() {
{
mockedMap.get(anyString);
result = "Success";
}
};
Object value = context.getSysInfo().get("test");
System.out.println(value);
}
}