HHH-16798 Add test for issue

hibernate-core/src/test/java/org/hibernate/orm/test/inheritance/LeftJoinFetchSubclassesTest.java

@@ -0,0 +1,175 @@
+/*
+ * 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.inheritance;
+
+import java.util.List;
+
+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.DiscriminatorValue;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Inheritance;
+import jakarta.persistence.InheritanceType;
+import jakarta.persistence.OneToOne;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Marco Belladelli
+ */
+@SessionFactory
+@DomainModel( annotatedClasses = {
+		LeftJoinFetchSubclassesTest.Entity1.class,
+		LeftJoinFetchSubclassesTest.SuperClass.class,
+		LeftJoinFetchSubclassesTest.SubClass1.class,
+		LeftJoinFetchSubclassesTest.SubClass2.class,
+} )
+@Jira( "https://hibernate.atlassian.net/browse/HHH-16798" )
+public class LeftJoinFetchSubclassesTest {
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final Entity1 entity1A = new Entity1( 1L );
+			session.persist( entity1A );
+			final SubClass1 subClass1 = new SubClass1();
+			subClass1.setId( 2L );
+			subClass1.setEntity1( entity1A );
+			session.persist( subClass1 );
+			final Entity1 entity1B = new Entity1( 3L );
+			session.persist( entity1B );
+			final SubClass2 subClass2 = new SubClass2();
+			subClass2.setId( 4L );
+			subClass2.setEntity1( entity1B );
+			session.persist( subClass2 );
+		} );
+	}
+
+	@AfterAll
+	public void tearDown(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			session.createMutationQuery( "delete from SuperClass" ).executeUpdate();
+			session.createMutationQuery( "delete from Entity1" ).executeUpdate();
+		} );
+	}
+
+	@Test
+	public void testJoinFetchSub1(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final Entity1 entity1 = session.createQuery(
+					"select e from Entity1 e left join fetch e.subClass1 where e.id = 1",
+					Entity1.class
+			).getSingleResult();
+			assertThat( entity1.getSubClass1().getId() ).isEqualTo( 2L );
+			assertThat( entity1.getSubClass2() ).isNull();
+		} );
+	}
+
+	@Test
+	public void testJoinFetchSub2(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final Entity1 entity1 = session.createQuery(
+					"select e from Entity1 e left join fetch e.subClass2 where e.id = 3",
+					Entity1.class
+			).getSingleResult();
+			assertThat( entity1.getSubClass1() ).isNull();
+			assertThat( entity1.getSubClass2().getId() ).isEqualTo( 4L );
+		} );
+	}
+
+	@Test
+	public void testJoinFetchBoth(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final List<Entity1> resultList = session.createQuery(
+					"select e from Entity1 e left join fetch e.subClass1 left join fetch e.subClass2",
+					Entity1.class
+			).getResultList();
+			assertThat( resultList ).hasSize( 2 );
+		} );
+	}
+
+	@Test
+	public void testJoinBoth(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final List<Entity1> resultList = session.createQuery(
+					"select e from Entity1 e left join e.subClass1 left join e.subClass2",
+					Entity1.class
+			).getResultList();
+			assertThat( resultList ).hasSize( 2 );
+		} );
+	}
+
+	@Entity( name = "Entity1" )
+	public static class Entity1 {
+		@Id
+		private Long id;
+
+		public Entity1() {
+		}
+
+		public Entity1(Long id) {
+			this.id = id;
+		}
+
+		@OneToOne( fetch = FetchType.LAZY, mappedBy = "entity1" )
+		private SubClass1 subClass1;
+
+		@OneToOne( fetch = FetchType.LAZY, mappedBy = "entity1" )
+		private SubClass2 subClass2;
+
+		public SubClass1 getSubClass1() {
+			return subClass1;
+		}
+
+		public SubClass2 getSubClass2() {
+			return subClass2;
+		}
+	}
+
+	@Entity( name = "SuperClass" )
+	@Inheritance( strategy = InheritanceType.SINGLE_TABLE )
+	public static abstract class SuperClass {
+		@Id
+		private Long id;
+
+		@OneToOne
+		private Entity1 entity1;
+
+		public Long getId() {
+			return id;
+		}
+
+		public void setId(Long id) {
+			this.id = id;
+		}
+
+		public Entity1 getEntity1() {
+			return entity1;
+		}
+
+		public void setEntity1(Entity1 entity1) {
+			this.entity1 = entity1;
+		}
+	}
+
+	@Entity( name = "SubClass1" )
+	@DiscriminatorValue( "1" )
+	public static class SubClass1 extends SuperClass {
+	}
+
+	@Entity( name = "SubClass2" )
+	@DiscriminatorValue( "2" )
+	public static class SubClass2 extends SuperClass {
+	}
+}