HHH-17131 Add test for issue

hibernate-core/src/test/java/org/hibernate/orm/test/stream/basic/NestedCollectionFetchStreamTest.java

@@ -0,0 +1,134 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
+ */
+package org.hibernate.orm.test.stream.basic;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.Jira;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.MappedSuperclass;
+import jakarta.persistence.OneToMany;
+import jakarta.persistence.Tuple;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Marco Belladelli
+ */
+@DomainModel( annotatedClasses = {
+		NestedCollectionFetchStreamTest.BasicEntity.class,
+		NestedCollectionFetchStreamTest.EntityA.class,
+		NestedCollectionFetchStreamTest.EntityB.class,
+		NestedCollectionFetchStreamTest.EntityC.class,
+} )
+@SessionFactory
+@Jira( "https://hibernate.atlassian.net/browse/HHH-17131" )
+public class NestedCollectionFetchStreamTest {
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final EntityB b = new EntityB();
+			b.getC().addAll( Stream.generate( EntityC::new ).limit( 3 ).collect( Collectors.toSet() ) );
+			session.persist( b );
+			session.persist( new EntityA( b ) );
+		} );
+	}
+
+	@AfterAll
+	public void tearDown(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			session.createMutationQuery( "delete from EntityA" ).executeUpdate();
+			session.createMutationQuery( "delete from EntityC" ).executeUpdate();
+			session.createMutationQuery( "delete from EntityB" ).executeUpdate();
+		} );
+	}
+
+	@Test
+	public void testImplicitNestedCollection(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			try (final Stream<EntityA> stream = session.createQuery(
+					"select a from EntityA a left join fetch a.b b left join fetch b.c c",
+					EntityA.class
+			).getResultStream()) {
+				final List<EntityA> list = stream.collect( Collectors.toList() );
+				assertThat( list ).hasSize( 1 );
+				assertThat( list.get( 0 ).getB() ).isNotNull();
+				assertThat( list.get( 0 ).getB().getC() ).hasSize( 3 );
+			}
+		} );
+	}
+
+	@Test
+	public void testExplicitNestedCollection(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			try (final Stream<Tuple> stream = session.createQuery(
+					"select a, b from EntityA a left join fetch a.b b left join fetch b.c c",
+					Tuple.class
+			).getResultStream()) {
+				final List<Tuple> list = stream.collect( Collectors.toList() );
+				assertThat( list ).hasSize( 1 );
+				assertThat( list.get( 0 ).get( 1, EntityB.class ) ).isNotNull();
+				assertThat( list.get( 0 ).get( 1, EntityB.class ).getC() ).hasSize( 3 );
+			}
+		} );
+	}
+
+	@MappedSuperclass
+	public static abstract class BasicEntity {
+		@Id
+		@GeneratedValue
+		private Long id;
+	}
+
+	@Entity( name = "EntityA" )
+	public static class EntityA extends BasicEntity {
+		@ManyToOne
+		private EntityB b;
+
+		public EntityA() {
+		}
+
+		public EntityA(EntityB b) {
+			this.b = b;
+		}
+
+		public EntityB getB() {
+			return b;
+		}
+	}
+
+	@Entity( name = "EntityB" )
+	public static class EntityB extends BasicEntity {
+		@OneToMany( cascade = CascadeType.PERSIST )
+		@JoinColumn( name = "entityb_id" )
+		private Set<EntityC> c = new HashSet<>();
+
+		public Set<EntityC> getC() {
+			return c;
+		}
+	}
+
+	@Entity( name = "EntityC" )
+	public static class EntityC extends BasicEntity {
+	}
+}