From 9029d76604c5b4330ab52782a50556a32a7a101d Mon Sep 17 00:00:00 2001
From: Marco Belladelli <marco@hibernate.org>
Date: Wed, 2 Aug 2023 15:31:08 +0200
Subject: [PATCH] HHH-16616 Add test for issue

---
 .../ManyToOneInheritanceSubTypeTest.java      | 149 ++++++++++++++++++
 1 file changed, 149 insertions(+)
 create mode 100644 hibernate-core/src/test/java/org/hibernate/orm/test/mapping/inheritance/ManyToOneInheritanceSubTypeTest.java

diff --git a/hibernate-core/src/test/java/org/hibernate/orm/test/mapping/inheritance/ManyToOneInheritanceSubTypeTest.java b/hibernate-core/src/test/java/org/hibernate/orm/test/mapping/inheritance/ManyToOneInheritanceSubTypeTest.java
new file mode 100644
index 0000000000..6eff309bae
--- /dev/null
+++ b/hibernate-core/src/test/java/org/hibernate/orm/test/mapping/inheritance/ManyToOneInheritanceSubTypeTest.java
@@ -0,0 +1,149 @@
+/*
+ * 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.mapping.inheritance;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.hibernate.testing.jdbc.SQLStatementInspector;
+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.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.DiscriminatorColumn;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.Inheritance;
+import jakarta.persistence.InheritanceType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.OneToMany;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Laurent Almeras
+ */
+@DomainModel( annotatedClasses = {
+		ManyToOneInheritanceSubTypeTest.SuperType.class,
+		ManyToOneInheritanceSubTypeTest.TypeA.class,
+		ManyToOneInheritanceSubTypeTest.TypeB.class,
+		ManyToOneInheritanceSubTypeTest.LinkedEntity.class
+} )
+@SessionFactory( useCollectingStatementInspector = true )
+@Jira( "https://hibernate.atlassian.net/browse/HHH-16616" )
+public class ManyToOneInheritanceSubTypeTest {
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final SuperType superType = new SuperType( 1 );
+			final TypeB typeB = new TypeB( 2, "typeB" );
+			final TypeA typeA = new TypeA( 3, "typeA" );
+			final LinkedEntity entity = new LinkedEntity( 4 );
+			entity.addTypeA( typeA );
+			session.persist( superType );
+			session.persist( typeB );
+			session.persist( typeA );
+			session.persist( entity );
+		} );
+	}
+
+	@Test
+	public void testFind(SessionFactoryScope scope) {
+		final SQLStatementInspector inspector = scope.getCollectingStatementInspector();
+		inspector.clear();
+		scope.inTransaction( session -> {
+			final LinkedEntity entity = session.find( LinkedEntity.class, 4 );
+			assertThat( entity.getTypeAS() ).hasSize( 1 );
+			inspector.assertExecutedCount( 2 );
+			inspector.assertNumberOfOccurrenceInQueryNoSpace( 1, "disc_col", 1 );
+		} );
+	}
+
+	@Test
+	public void testJoinFetch(SessionFactoryScope scope) {
+		final SQLStatementInspector inspector = scope.getCollectingStatementInspector();
+		inspector.clear();
+		scope.inTransaction( session -> {
+			final LinkedEntity entity = session.createQuery(
+					"from LinkedEntity e left join fetch e.typeAS",
+					LinkedEntity.class
+			).getSingleResult();
+			assertThat( entity.getTypeAS() ).hasSize( 1 );
+			inspector.assertExecutedCount( 1 );
+			inspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "disc_col", 1 );
+		} );
+	}
+
+	@Entity( name = "SuperType" )
+	@Inheritance( strategy = InheritanceType.SINGLE_TABLE )
+	@DiscriminatorColumn( name = "disc_col" )
+	public static class SuperType {
+		@Id
+		private Integer id;
+
+		public SuperType() {
+		}
+
+		public SuperType(Integer id) {
+			this.id = id;
+		}
+	}
+
+	@Entity( name = "TypeA" )
+	public static class TypeA extends SuperType {
+		private String typeAName;
+
+		public TypeA() {
+		}
+
+		public TypeA(Integer id, String typeAName) {
+			super( id );
+			this.typeAName = typeAName;
+		}
+	}
+
+	@Entity( name = "TypeB" )
+	public static class TypeB extends SuperType {
+		private String typeBName;
+
+		public TypeB() {
+		}
+
+		public TypeB(Integer id, String typeBName) {
+			super( id );
+			this.typeBName = typeBName;
+		}
+	}
+
+	@Entity( name = "LinkedEntity" )
+	public static class LinkedEntity {
+		@Id
+		private Integer id;
+
+		@OneToMany
+		@JoinColumn( name = "linked_id" )
+		private List<TypeA> typeAS = new ArrayList<>();
+
+		public LinkedEntity() {
+		}
+
+		public LinkedEntity(Integer id) {
+			this.id = id;
+		}
+
+		public List<TypeA> getTypeAS() {
+			return typeAS;
+		}
+
+		public void addTypeA(TypeA typeA) {
+			this.typeAS.add( typeA );
+		}
+	}
+}