BZ-1019708: fixing NPE on queries with no results

(cherry picked from commit 315cc8f)

drools-compiler/src/test/java/org/drools/compiler/integrationtests/QueryCepTest.java

@@ -0,0 +1,138 @@
+package org.drools.compiler.integrationtests;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.concurrent.TimeUnit;
+
+import org.drools.core.time.SessionPseudoClock;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Ignore;
+import org.junit.Test;
+import org.kie.api.KieServices;
+import org.kie.api.builder.KieFileSystem;
+import org.kie.api.builder.model.KieBaseModel;
+import org.kie.api.builder.model.KieModuleModel;
+import org.kie.api.conf.EventProcessingOption;
+import org.kie.api.runtime.KieSession;
+import org.kie.api.runtime.conf.ClockTypeOption;
+import org.kie.api.runtime.rule.EntryPoint;
+import org.kie.api.runtime.rule.QueryResults;
+import org.kie.internal.io.ResourceFactory;
+
+public class QueryCepTest {
+
+    private KieSession ksession;
+
+    private SessionPseudoClock clock;
+
+    private EntryPoint firstEntryPoint, secondEntryPoint;
+
+    @Before
+    public void prepare() {
+        String drl = "package org.drools.compiler.integrationtests\n" + 
+                "import org.drools.compiler.integrationtests.QueryCepTest.TestEvent\n" + 
+                "declare TestEvent\n" + 
+                "    @role( event )\n" + 
+                "end\n" + 
+                "query EventsFromStream\n" + 
+                "    $event : TestEvent() from entry-point FirstStream\n" + 
+                "end\n" + 
+                "query ZeroToNineteenSeconds\n" + 
+                "    $event : TestEvent() from entry-point FirstStream\n" + 
+                "    $result : TestEvent ( this after [0s, 19s] $event) from entry-point SecondStream\n" + 
+                "end\n";
+
+        final KieServices ks = KieServices.Factory.get();
+        KieFileSystem kfs = ks.newKieFileSystem();
+        KieModuleModel kmodule = ks.newKieModuleModel();
+
+        KieBaseModel baseModel = kmodule.newKieBaseModel("defaultKBase")
+                .setDefault(true)
+                .setEventProcessingMode(EventProcessingOption.STREAM);
+        baseModel.newKieSessionModel("defaultKSession")
+                .setDefault(true)
+                .setClockType(ClockTypeOption.get("pseudo"));
+
+        kfs.writeKModuleXML(kmodule.toXML());
+        kfs.write( ResourceFactory.newByteArrayResource(drl.getBytes())
+                                  .setTargetPath("org/drools/compiler/integrationtests/queries.drl") );
+
+        assertTrue(ks.newKieBuilder(kfs).buildAll().getResults().getMessages().isEmpty());
+        ksession = ks.newKieContainer(ks.getRepository().getDefaultReleaseId()).newKieSession();
+
+        firstEntryPoint = ksession.getEntryPoint("FirstStream");
+        secondEntryPoint = ksession.getEntryPoint("SecondStream"); 
+        clock = ksession.getSessionClock();
+    }
+
+    @Test
+    public void noResultTest() {
+        QueryResults results = ksession.getQueryResults("EventsFromStream");
+        assertEquals(0, results.size());
+    }
+
+    @Test
+    public void withResultTest() {
+        secondEntryPoint.insert(new TestEvent("minusOne"));
+        clock.advanceTime(5, TimeUnit.SECONDS);
+
+        firstEntryPoint.insert(new TestEvent("zero"));
+        secondEntryPoint.insert(new TestEvent("one"));
+        clock.advanceTime(10, TimeUnit.SECONDS);
+
+        secondEntryPoint.insert(new TestEvent("two"));
+        clock.advanceTime(5, TimeUnit.SECONDS);
+
+        secondEntryPoint.insert(new TestEvent("three"));
+        QueryResults results = ksession.getQueryResults("ZeroToNineteenSeconds");
+
+        assertEquals(3, results.size());
+    }
+
+    @Test
+    public void withNoResultTest() {
+        secondEntryPoint.insert(new TestEvent("minusOne"));
+        clock.advanceTime(5, TimeUnit.SECONDS);
+
+        firstEntryPoint.insert(new TestEvent("zero"));
+        secondEntryPoint.insert(new TestEvent("one"));
+        clock.advanceTime(10, TimeUnit.SECONDS);
+
+        secondEntryPoint.insert(new TestEvent("two"));
+        // the following expires event "zero" and "one", causing the query to no longer match
+        clock.advanceTime(10, TimeUnit.SECONDS); 
+
+        secondEntryPoint.insert(new TestEvent("three"));
+        QueryResults results = ksession.getQueryResults("ZeroToNineteenSeconds");
+
+        assertEquals(0, results.size());
+    }
+
+    @After
+    public void cleanup() {
+
+        if (ksession != null) {
+            ksession.dispose();
+        }
+    }
+
+    public static class TestEvent {
+
+        private final String name;
+
+        public TestEvent(final String name) {
+            this.name = name;
+        }
+
+        public String getName() {
+            return this.name;
+        }        
+
+        @Override
+        public String toString() {
+            return "TestEvent[" + name + "]";
+        }
+    }
+}

drools-core/src/main/java/org/drools/core/common/AbstractWorkingMemory.java

@@ -544,7 +544,7 @@ private BaseNode[] evalQuery(String queryName, DroolsQuery queryObject, Internal
             lmem.linkNode(this);
             List<PathMemory> pmems =  lmem.getSegmentMemory().getPathMemories();
             PathMemory pmm = pmems!=null && !pmems.isEmpty() ? pmems.get(0) : null;
-            if( pmm != null ) {
+            if( pmm != null && pmm.getRuleAgendaItem() != null ) {
                 RuleAgendaItem item = pmm.getRuleAgendaItem();
                 item.getRuleExecutor().reEvaluateNetwork( this, new org.drools.core.util.LinkedList<StackEntry>(), false);
             }