Query order can to lead to a NPE -------------------------------- Key: DROOLS-770 URL: https://issues.jboss.org/browse/DROOLS-770 Project: Drools Issue Type: Bug Reporter: Jonathan MERCIER Assignee: Mario Fusco Priority: Critical Fix For: 6.4.0.CR1 This bug is already reported to the drools team via email on 13th february. To follow efficiently any progress on this critical bug, I open a ticket. So, the reproducer code is: {code:java|title=NpeOnQueryTest|borderStyle=solid} package org.drools.compiler.integrationtests; import org.junit.Test; import org.kie.api.io.ResourceType; import org.kie.api.runtime.KieSession; import org.kie.internal.utils.KieHelper; import java.util.List; public class NpeOnQueryTest { @Test public void test() { String drl = "import " + FiveState.class.getCanonicalName() + ";\n" + "import " + NodeType.class.getCanonicalName() + ";\n" + "import " + Knowledge.class.getCanonicalName() + ";\n" + "import " + List.class.getCanonicalName() + ";\n" + "\n" + "rule \"Or Knowledge is unknown\"\n" + " when\n" + " $k: Knowledge( presence == FiveState.UNEVALUATED, nodeType == NodeType.OR )\n" + " allSubKnowledgeAreEvaluated( $k, $childs; )\n" + " not( Knowledge( presence == FiveState.TRUE ) )\n" + " then\n" + " modify( $k ){\n" + " setPresence( FiveState.UNKNOWN )\n" + " }\n" + "end\n" + "\n" + "rule \"Or Knowledge is present\"\n" + " when\n" + " $k: Knowledge( presence == FiveState.UNEVALUATED, nodeType == NodeType.OR )\n" + " allSubKnowledgeAreEvaluated( $k, $childs; )\n" + " then\n" + " modify( $k ){\n" + " setPresence( FiveState.TRUE )\n" + " }\n" + "end\n" + "\n" + "query allSubKnowledgeAreEvaluated( Knowledge parent, List childs )\n" + " childs:= List() from collect ( Knowledge( parent memberOf partOf ))\n" + " forall( Knowledge( presence != FiveState.UNEVALUATED ) from childs )\n" + "end\n"; KieSession ksession = new KieHelper().addContent(drl, ResourceType.DRL) .build() .newKieSession(); Knowledge bk0 = new Knowledge(new Knowledge[0], NodeType.OR, "bk0", FiveState.UNEVALUATED); Knowledge bk1 = new Knowledge(new Knowledge[] { bk0 }, NodeType.LEAF, "bk1", FiveState.TRUE); ksession.insert( bk0 ); ksession.insert( bk1 ); ksession.fireAllRules(); } public enum FiveState { TRUE, FALSE, BOTH, UNKNOWN, UNEVALUATED } public enum NodeType { LEAF, AND, OR } public static class Knowledge { private final Knowledge[] partOf; private final NodeType nodeType; private final String name; private FiveState presence; public Knowledge(Knowledge[] partOf, NodeType nodeType, String name, FiveState presence) { this.partOf = partOf; this.nodeType = nodeType; this.name = name; this.presence = presence; } public void setPresence(final FiveState presence) { this.presence = presence; } public String getName() { return name; } public FiveState getPresence() { return presence; } public NodeType getNodeType() { return nodeType; } public Knowledge[] getPartOf() { return partOf; } } } {code} The interesting thing to be noticed is that if I move the query before the 2 rules in that DRL the problem disappears.