There is a test case in class: https://github.com/droolsjbpm/jbpm/blob/master/jbpm-examples/src/test/java/org/jbpm/examples/junit/BPMN2JUnitTests.java of jpm-example project. The problem is that it doesn't work for me. For you?
But you can define a rule with drools expert to start a process:
rule "start process rule"
timer (cron: 0 0 6 * * ?)
when
then
System.out.println("start process");
insert(kcontext.getKnowledgeRuntime().startProcess("receiveMessage"));
end
see: https://community.jboss.org/thread/201452