KieServices ks = KieServices.Factory.get();
KieFileSystem kfs = ks.newKieFileSystem();
kfs.write(ResourceFactory.newByteArrayResource(str.getBytes()).setTargetPath("org/drools/compiler/rules.drl") );
KieBuilder kbuilder = KieServices.Factory.get().newKieBuilder(kfs);
kbuilder.buildAll();
assertEquals(0, kbuilder.getResults().getMessages().size());
ks.newKieContainer(kbuilder.getKieModule().getReleaseId()).getKieBase();
KieSession ksession = ks.newKieContainer(kbuilder.getKieModule().getReleaseId()).newKieSession();