HHH-16559 Add test for issue

hibernate-core/src/test/java/org/hibernate/orm/test/batch/BatchFetchInstantiationTest.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.batch;
+
+import org.hibernate.cfg.AvailableSettings;
+
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.Jira;
+import org.hibernate.testing.orm.junit.ServiceRegistry;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.hibernate.testing.orm.junit.Setting;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.TypedQuery;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Marco Belladelli
+ */
+@SessionFactory
+@DomainModel( annotatedClasses = {
+		BatchFetchInstantiationTest.EntityA.class,
+		BatchFetchInstantiationTest.EntityB.class,
+		BatchFetchInstantiationTest.MyPojo.class
+} )
+@ServiceRegistry( settings = @Setting( name = AvailableSettings.DEFAULT_BATCH_FETCH_SIZE, value = "2" ) )
+@Jira( "https://hibernate.atlassian.net/browse/HHH-16559" )
+public class BatchFetchInstantiationTest {
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final EntityB entityB = new EntityB( "entity_b" );
+			session.persist( entityB );
+			session.persist( new EntityA( 1L, entityB ) );
+		} );
+	}
+
+	@AfterAll
+	public void tearDown(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			session.createMutationQuery( "delete from EntityA" ).executeUpdate();
+			session.createMutationQuery( "delete from EntityB" ).executeUpdate();
+		} );
+	}
+
+	@Test
+	public void testNormalSelect(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final TypedQuery<EntityA> query = session.createQuery(
+					"select t from EntityA t where t.id = ?1",
+					EntityA.class
+			).setParameter( 1, 1L );
+			final EntityA result = query.getSingleResult();
+			assertThat( result.getEntityB().getName() ).isEqualTo( "entity_b" );
+		} );
+	}
+
+	@Test
+	public void testDynamicInstantiation(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final TypedQuery<MyPojo> query2 = session.createQuery(
+					String.format( "select new %s(t) from EntityA t where t.id = ?1", MyPojo.class.getName() ),
+					MyPojo.class
+			).setParameter( 1, 1L );
+			final MyPojo pojo = query2.getSingleResult();
+			assertThat( pojo.getName() ).isEqualTo( "entity_b" );
+		} );
+	}
+
+	@Entity( name = "EntityA" )
+	public static class EntityA {
+		@Id
+		private Long id;
+
+		@ManyToOne
+		private EntityB entityB;
+
+		public EntityA() {
+		}
+
+		public EntityA(Long id, EntityB entityB) {
+			this.id = id;
+			this.entityB = entityB;
+		}
+
+		public EntityB getEntityB() {
+			return entityB;
+		}
+	}
+
+	@Entity( name = "EntityB" )
+	public static class EntityB {
+		@Id
+		@GeneratedValue
+		private Long id;
+
+		private String name;
+
+		public EntityB() {
+		}
+
+		public EntityB(String name) {
+			this.name = name;
+		}
+
+		public String getName() {
+			return name;
+		}
+	}
+
+	public static class MyPojo {
+		private final String name;
+
+		public MyPojo(EntityA a) {
+			this.name = a.getEntityB().getName();
+		}
+
+		public String getName() {
+			return name;
+		}
+	}
+}