Modified unit test to test finding knowledge gaps in loop scenarios.

smart-connector/src/main/java/eu/knowledge/engine/smartconnector/impl/ReasonerProcessor.java

@@ -194,7 +194,7 @@ public CompletableFuture<AskResult> executeAskInteraction(BindingSet someBinding
 
 		return this.finalBindingSetFuture.thenApply((bs) -> {
 			if (myKnowledgeInteraction.getKnowledgeInteraction().knowledgeGapsEnabled()) {
-				this.knowledgeGaps = bs.isEmpty() ? getKnowledgeGaps(this.reasonerPlan.getStartNode())
+				this.knowledgeGaps = bs.isEmpty() ? getKnowledgeGaps(this.reasonerPlan.getStartNode(), new HashSet<>())
 						: new HashSet<KnowledgeGap>();
 			}
 
@@ -666,15 +666,17 @@ public ReasonerPlan getReasonerPlan() {
 	 *         {@code A} <i><b>AND</b></i> {@code B} need to be added to solve the
 	 *         gap.
 	 */
-	public Set<KnowledgeGap> getKnowledgeGaps(RuleNode plan) {
+	public Set<KnowledgeGap> getKnowledgeGaps(RuleNode node, Set<RuleNode> someVisitedNodes) {
 
-		assert plan instanceof AntSide;
+		assert node instanceof AntSide;
 
 		Set<KnowledgeGap> existingOrGaps = new HashSet<>();
 
+		someVisitedNodes.add(node);
+
 		// TODO do we need to include the parent if we are not backward chaining?
-		Map<TriplePattern, Set<RuleNode>> nodeCoverage = plan
-				.findAntecedentCoverage(((AntSide) plan).getAntecedentNeighbours());
+		Map<TriplePattern, Set<RuleNode>> nodeCoverage = node
+				.findAntecedentCoverage(((AntSide) node).getAntecedentNeighbours());
 
 		// collect triple patterns that have an empty set
 		Set<KnowledgeGap> collectedOrGaps, someGaps = new HashSet<>();
@@ -689,7 +691,7 @@ public Set<KnowledgeGap> getKnowledgeGaps(RuleNode plan) {
 			for (RuleNode neighbor : entry.getValue()) {
 				LOG.trace("Neighbor is {}", neighbor);
 
-				if (!neighbor.getRule().getAntecedent().isEmpty()) {
+				if (!someVisitedNodes.contains(neighbor) && !neighbor.getRule().getAntecedent().isEmpty()) {
 					// make sure neighbor has no knowledge gaps
 					LOG.trace("Neighbor has antecedents, so check if the neighbor has gaps");
 
@@ -699,7 +701,7 @@ public Set<KnowledgeGap> getKnowledgeGaps(RuleNode plan) {
 					boolean isMeta = isMetaKI(neighbor);
 
 					// TODO what if the graph contains loops?
-					if (!isMeta && (someGaps = getKnowledgeGaps(neighbor)).isEmpty()) {
+					if (!isMeta && (someGaps = getKnowledgeGaps(neighbor, someVisitedNodes)).isEmpty()) {
 						// found neighbor without knowledge gaps for the current triple, so current
 						// triple is covered.
 						LOG.trace("Neighbor has no gaps");

smart-connector/src/test/java/eu/knowledge/engine/smartconnector/api/GeneralizeIfNecessaryTest.java

@@ -1,6 +1,7 @@
 package eu.knowledge.engine.smartconnector.api;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 
 import java.util.Arrays;
 import java.util.HashSet;
@@ -61,6 +62,7 @@ public void test() throws InterruptedException, ExecutionException {
 
 		BindingSet argument = new BindingSet();
 		Binding binding = new Binding();
+		binding.put("b", "<http://example.org/building1>");
 		argument.add(binding);
 		AskPlan pp = appKb.planAsk(appKbAsk, new RecipientSelector());
 
@@ -72,22 +74,34 @@ public void test() throws InterruptedException, ExecutionException {
 		BindingSet expectedBS = new BindingSet();
 		Binding expectedB = new Binding();
 		expectedB.put("s", "<http://example.org/sensor1>");
+		expectedB.put("b", "<http://example.org/building1>");
 		expectedB.put("value", "\"10\"^^<http://www.w3.org/2001/XMLSchema#integer>");
 		expectedBS.add(expectedB);
 
 		expectedB = new Binding();
 		expectedB.put("s", "<http://example.org/sensor2>");
+		expectedB.put("b", "<http://example.org/building1>");
 		expectedB.put("value", "\"20\"^^<http://www.w3.org/2001/XMLSchema#integer>");
 		expectedBS.add(expectedB);
 
 		assertEquals(expectedBS, result.getBindings());
 
+		// test again, but now trigger knowledge gaps detection (in loop scenario's like
+		// this test contains)
+		BindingSet bs = new BindingSet();
+		Binding b = new Binding();
+		b.put("b", "<http://example.org/building3>");
+		bs.add(b);
+		AskResult ar = appKb.ask(appKbAsk, bs).get();
+		assertNotNull(ar);
+
 	}
 
 	private AskKnowledgeInteraction configureAppKb() {
 		GraphPattern appGP = new GraphPattern(prefixes,
-				"?s rdf:type ex:Sensor . ?s ex:isPartOf ex:building1 . ?s ex:hasLatestValue ?value .");
-		AskKnowledgeInteraction appKbAsk = new AskKnowledgeInteraction(new CommunicativeAct(), appGP);
+				"?s rdf:type ex:Sensor . ?s ex:isPartOf ?b . ?s ex:hasLatestValue ?value .");
+		AskKnowledgeInteraction appKbAsk = new AskKnowledgeInteraction(new CommunicativeAct(), appGP, "askLatestValue",
+				true);
 		appKb.register(appKbAsk);
 
 		HashSet<TriplePattern> rule1ant = new HashSet<>(