Migrate constant PathFindingResult.EMPTY to method

Co-authored-by: Ioannis Panagiotas <ioannis.panagiotas@neotechnology.com>

Author: vnickolov

algo/src/main/java/org/neo4j/gds/paths/bellmanford/BellmanFordResult.java

@@ -27,8 +27,8 @@ public record BellmanFordResult(
     boolean containsNegativeCycle
 ) {
     public static final BellmanFordResult EMPTY = new BellmanFordResult(
-        PathFindingResult.EMPTY,
-        PathFindingResult.EMPTY,
+        PathFindingResult.empty(),
+        PathFindingResult.empty(),
         false
     );
 

algo/src/main/java/org/neo4j/gds/paths/dijkstra/PathFindingResult.java

@@ -31,8 +31,6 @@
 
 public class PathFindingResult {
 
-    public static final PathFindingResult EMPTY = new PathFindingResult(Stream.empty());
-
     private final Stream<PathResult> paths;
 
     private final Runnable closeStreamAction;
@@ -75,4 +73,8 @@ private void runConsumptionAction() {
             closeStreamAction.run();
         }
     }
+
+    public static PathFindingResult empty() {
+        return new PathFindingResult(Stream.empty());
+    }
 }

algorithms-compute-facade/src/main/java/org/neo4j/gds/pathfinding/PathFindingComputeFacade.java

@@ -228,7 +228,7 @@ public CompletableFuture<PathFindingResult> deltaStepping(
     ) {
         // If the input graph is empty return a completed future with empty result
         if (graph.isEmpty()) {
-            return CompletableFuture.completedFuture(PathFindingResult.EMPTY);
+            return CompletableFuture.completedFuture(PathFindingResult.empty());
         }
 
         // Create ProgressTracker
@@ -334,7 +334,7 @@ public CompletableFuture<PathFindingResult> longestPath(
     ) {
         // If the input graph is empty return a completed future with empty result
         if (graph.isEmpty()) {
-            return CompletableFuture.completedFuture(PathFindingResult.EMPTY);
+            return CompletableFuture.completedFuture(PathFindingResult.empty());
         }
 
         // Create ProgressTracker
@@ -474,7 +474,7 @@ public CompletableFuture<PathFindingResult> singlePairShortestPathAStar(
     ) {
         // If the input graph is empty return a completed future with empty result
         if (graph.isEmpty()) {
-            return CompletableFuture.completedFuture(PathFindingResult.EMPTY);
+            return CompletableFuture.completedFuture(PathFindingResult.empty());
         }
 
         // Create ProgressTracker
@@ -508,7 +508,7 @@ public CompletableFuture<PathFindingResult> singlePairShortestPathDijkstra(
     ) {
         // If the input graph is empty return a completed future with empty result
         if (graph.isEmpty()) {
-            return CompletableFuture.completedFuture(PathFindingResult.EMPTY);
+            return CompletableFuture.completedFuture(PathFindingResult.empty());
         }
 
         // Create ProgressTracker
@@ -545,7 +545,7 @@ public CompletableFuture<PathFindingResult> singlePairShortestPathYens(
     ) {
         // If the input graph is empty return a completed future with empty result
         if (graph.isEmpty()) {
-            return CompletableFuture.completedFuture(PathFindingResult.EMPTY);
+            return CompletableFuture.completedFuture(PathFindingResult.empty());
         }
 
         // Create ProgressTracker
@@ -582,7 +582,7 @@ public CompletableFuture<PathFindingResult> singleSourceShortestPathDijkstra(
     ) {
         // If the input graph is empty return a completed future with empty result
         if (graph.isEmpty()) {
-            return CompletableFuture.completedFuture(PathFindingResult.EMPTY);
+            return CompletableFuture.completedFuture(PathFindingResult.empty());
         }
 
         // Create ProgressTracker

algorithms-compute-facade/src/test/java/org/neo4j/gds/pathfinding/PathFindingComputeFacadeEmptyGraphTest.java

@@ -53,6 +53,7 @@
 import org.neo4j.gds.traversal.TraversalParameters;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.InstanceOfAssertFactories.SET;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verifyNoInteractions;
 import static org.mockito.Mockito.when;
@@ -142,7 +143,11 @@ void deltaStepping() {
         );
         var result = future.join();
 
-        assertThat(result).isNotNull().isEqualTo(PathFindingResult.EMPTY);
+        assertThat(result)
+            .isNotNull()
+            .extracting(PathFindingResult::pathSet)
+            .asInstanceOf(SET)
+            .isEmpty();
 
         verifyNoInteractions(progressTrackerFactoryMock);
         verifyNoInteractions(algorithmCallerMock);
@@ -191,7 +196,11 @@ void longestPath() {
         );
         var result = future.join();
 
-        assertThat(result).isNotNull().isEqualTo(PathFindingResult.EMPTY);
+        assertThat(result)
+            .isNotNull()
+            .extracting(PathFindingResult::pathSet)
+            .asInstanceOf(SET)
+            .isEmpty();
 
         verifyNoInteractions(progressTrackerFactoryMock);
         verifyNoInteractions(algorithmCallerMock);
@@ -257,7 +266,11 @@ void singlePairShortestPathAStar() {
         );
         var result = future.join();
 
-        assertThat(result).isNotNull().isEqualTo(PathFindingResult.EMPTY);
+        assertThat(result)
+            .isNotNull()
+            .extracting(PathFindingResult::pathSet)
+            .asInstanceOf(SET)
+            .isEmpty();
 
         verifyNoInteractions(progressTrackerFactoryMock);
         verifyNoInteractions(algorithmCallerMock);
@@ -273,7 +286,11 @@ void singlePairShortestPathDijkstra() {
         );
         var result = future.join();
 
-        assertThat(result).isNotNull().isEqualTo(PathFindingResult.EMPTY);
+        assertThat(result)
+            .isNotNull()
+            .extracting(PathFindingResult::pathSet)
+            .asInstanceOf(SET)
+            .isEmpty();
 
         verifyNoInteractions(progressTrackerFactoryMock);
         verifyNoInteractions(algorithmCallerMock);
@@ -289,7 +306,11 @@ void singlePairShortestPathYens() {
         );
         var result = future.join();
 
-        assertThat(result).isNotNull().isEqualTo(PathFindingResult.EMPTY);
+        assertThat(result)
+            .isNotNull()
+            .extracting(PathFindingResult::pathSet)
+            .asInstanceOf(SET)
+            .isEmpty();
 
         verifyNoInteractions(progressTrackerFactoryMock);
         verifyNoInteractions(algorithmCallerMock);
@@ -305,7 +326,11 @@ void singleSourceShortestPathDijkstra() {
         );
         var result = future.join();
 
-        assertThat(result).isNotNull().isEqualTo(PathFindingResult.EMPTY);
+        assertThat(result)
+            .isNotNull()
+            .extracting(PathFindingResult::pathSet)
+            .asInstanceOf(SET)
+            .isEmpty();
 
         verifyNoInteractions(progressTrackerFactoryMock);
         verifyNoInteractions(algorithmCallerMock);

procedures/pushback-procedures-facade/src/test/java/org/neo4j/gds/procedures/algorithms/pathfinding/PathFindingStreamResultTransformerTest.java

@@ -50,7 +50,7 @@ void shouldReturnEmptyStreamOnEmptyResult() {
             pathFactoryFacadeMock
         );
 
-        var streamResult = transformer.apply(PathFindingResult.EMPTY);
+        var streamResult = transformer.apply(PathFindingResult.empty());
         assertThat(streamResult).isEmpty();
 
         verifyNoInteractions(graphMock);