GH-902 - Add more tests.

Author: michael-simons

core/src/main/java/org/neo4j/ogm/context/RestModelMapper.java

@@ -18,14 +18,13 @@
  */
 package org.neo4j.ogm.context;
 
-import static java.util.stream.Collectors.*;
-
 import java.lang.reflect.Array;
 import java.util.*;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.function.Predicate;
+import java.util.stream.Collectors;
 
 import org.neo4j.ogm.metadata.MetaData;
 import org.neo4j.ogm.model.GraphModel;
@@ -93,7 +92,7 @@ public String[] columns() {
         // Recreate the original structure
         RestStatisticsModel restStatisticsModel = new RestStatisticsModel();
         response.getStatistics().ifPresent(restStatisticsModel::setStatistics);
-        restStatisticsModel.setResult(resultRowBuilders.stream().map(ResultRowBuilder::finish).collect(toList()));
+        restStatisticsModel.setResult(resultRowBuilders.stream().map(ResultRowBuilder::finish).collect(Collectors.toList()));
         return restStatisticsModel;
     }
 
@@ -268,7 +267,8 @@ Map<String, Object> finish() {
                     Object entity = resolveNodeId.apply(v.get(0), graphModel);
                     resultRow.put(k, entity);
                 } else {
-                    List<Object> entities = v.stream().map(id -> resolveNodeId.apply(id, graphModel)).collect(toList());
+                    List<Object> entities = v.stream().map(id -> resolveNodeId.apply(id, graphModel)).collect(
+                        Collectors.toList());
                     List<Object> entityList = (List<Object>) resultRow.computeIfAbsent(k, key -> new ArrayList<>());
                     entityList.addAll(entities);
                 }
@@ -278,7 +278,7 @@ Map<String, Object> finish() {
                     Object entity = resolveRelationshipId.apply(v.get(0));
                     resultRow.put(k, entity);
                 } else {
-                    List<Object> entities = v.stream().map(resolveRelationshipId).collect(toList());
+                    List<Object> entities = v.stream().map(resolveRelationshipId).collect(Collectors.toList());
                     List<Object> entityList = (List<Object>) resultRow.computeIfAbsent(k, key -> new ArrayList<>());
                     entityList.addAll(entities);
                 }

neo4j-ogm-tests/neo4j-ogm-integration-tests/src/test/java/org/neo4j/ogm/persistence/model/EntityGraphMapperTest.java

@@ -982,4 +982,50 @@ public void collectedListOfNodesFromPathsShouldNotCollapse() {
                 });
         });
     }
+
+    @Test
+    public void emptyArray1Level() {
+
+        Result result = session.query("RETURN [] as x", Collections.emptyMap());
+        assertThat(result).hasSize(1).first().satisfies(row -> {
+            Object x = row.get("x");
+            assertThat(x).isInstanceOf(Void[].class);
+            assertThat(((Void[]) x)).isEmpty();
+        });
+    }
+
+    @Test
+    public void emptyArray2Level() {
+
+        Result result = session.query("RETURN [[]] as x", Collections.emptyMap());
+        assertThat(result).hasSize(1).first().satisfies(row -> {
+            Object x = row.get("x");
+            assertThat(x).isInstanceOf(Void[].class);
+            assertThat(((Void[]) x)).isEmpty();
+        });
+    }
+
+    @Test
+    public void empty2Dim1Level() {
+
+        Result result = session.query("RETURN [[], []] as x", Collections.emptyMap());
+        assertThat(result).hasSize(1).first().satisfies(row -> {
+            Object x = row.get("x");
+            assertThat(x).isInstanceOf(Void[].class);
+            assertThat(((Void[]) x)).isEmpty();
+        });
+    }
+
+    @Test // GH-902
+    @SuppressWarnings("unchecked")
+    public void emptyCollectedNodeList() {
+
+        Result result = session.query("MATCH p=(:AAA)-[*]->(:BBB) RETURN COLLECT (DISTINCT nodes(p)) AS paths",
+            Collections.emptyMap());
+        assertThat(result).hasSize(1).first().satisfies(row -> {
+            Object nestedLists = row.get("paths");
+            assertThat(nestedLists).isInstanceOf(Void[].class);
+            assertThat(((Void[]) nestedLists)).isEmpty();
+        });
+    }
 }