You need to use one of the "magic" castings of jBPM...
WorkflowProcessInstance process = (WorkflowProcessInstance) ksession.startProcess("some.id");
Assert.assertEquals("Ask for Emergency Information", process.getNodeInstances().iterator().next().getNodeName());
Remember that the active nodes are those that left the process instance in a waiting state. So, for example, you will never see a Script Task here.
You can also monitor entries into nodes by using method public void beforeNodeTriggered( ProcessNodeTriggeredEvent event )
of your implementation of org.drools.event.process.ProcessEventListener interface.