Test load of polymorphic entities

hibernate-core/src/test/java/org/hibernate/orm/test/polymorphic/PolymorphicAssociationTest.java

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+/*
+ * Hibernate Search, full-text search for your domain model
+ *
+ * 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.polymorphic;
+
+import org.hibernate.testing.junit4.BaseCoreFunctionalTestCase;
+
+import org.junit.Test;
+
+import jakarta.persistence.Basic;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.Id;
+import jakarta.persistence.OneToOne;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class PolymorphicAssociationTest extends BaseCoreFunctionalTestCase  {
+
+	@Override
+	protected Class<?>[] getAnnotatedClasses() {
+		return new Class[] { Level1.class, Level2.class, DerivedLevel2.class, Level3.class };
+	}
+
+	@Test
+	public void test() {
+		inTransaction( session -> {
+			Level1 level1 = new Level1();
+			level1.setId( 1 );
+			DerivedLevel2 level2 = new DerivedLevel2();
+			level2.setId( 2 );
+			Level3 level3 = new Level3();
+			level3.setId( 3 );
+
+			level1.setLevel2Child( level2 );
+			level2.setLevel1Parent( level1 );
+			level2.setLevel3Child( level3 );
+			level3.setLevel2Parent( level2 );
+
+			level3.setName( "initial-name" );
+
+			session.save( level1 );
+			session.save( level2 );
+			session.save( level3 );
+		} );
+
+		inTransaction( session -> {
+			Level3 level3 = session.load( Level3.class, 3 );
+			Level2 level2 = level3.getLevel2Parent();
+			assertThat( level2 ).isNotNull();
+			assertThat( level2.getLevel3Child() ).extracting( "id" ).isEqualTo( 3 );
+		} );
+
+		inTransaction( session -> {
+			Level1 level1 = session.load( Level1.class, 1 );
+			DerivedLevel2 level2 = level1.getLevel2Child();
+			assertThat( level2 ).isNotNull();
+			assertThat( level2.getLevel1Parent() ).extracting( "id" ).isEqualTo( 1 );
+		} );
+	}
+
+	@Entity(name = "Level1")
+	public static class Level1 {
+
+		@Id
+		private Integer id;
+
+		@OneToOne(mappedBy = "level1Parent")
+		private DerivedLevel2 level2Child;
+
+		public Integer getId() {
+			return id;
+		}
+
+		public void setId(Integer id) {
+			this.id = id;
+		}
+
+		public DerivedLevel2 getLevel2Child() {
+			return level2Child;
+		}
+
+		public void setLevel2Child(DerivedLevel2 level2Child) {
+			this.level2Child = level2Child;
+		}
+	}
+
+	@Entity(name = "Level2")
+	public static class Level2 {
+
+		@Id
+		private Integer id;
+
+		@OneToOne(mappedBy = "level2Parent")
+		private Level3 level3Child;
+
+		public Integer getId() {
+			return id;
+		}
+
+		public void setId(Integer id) {
+			this.id = id;
+		}
+
+		public Level3 getLevel3Child() {
+			return level3Child;
+		}
+
+		public void setLevel3Child(Level3 level3Child) {
+			this.level3Child = level3Child;
+		}
+	}
+
+	@Entity(name = "DerivedLevel2")
+	public static class DerivedLevel2 extends Level2 {
+
+		@OneToOne
+		private Level1 level1Parent;
+
+		public Level1 getLevel1Parent() {
+			return level1Parent;
+		}
+
+		public void setLevel1Parent(Level1 level1Parent) {
+			this.level1Parent = level1Parent;
+		}
+	}
+
+	@Entity(name = "Level3")
+	static class Level3 {
+
+		@Id
+		private Integer id;
+
+		@Basic
+		private String name;
+
+		@OneToOne(fetch = FetchType.LAZY)
+		private Level2 level2Parent;
+
+		public Integer getId() {
+			return id;
+		}
+
+		public void setId(Integer id) {
+			this.id = id;
+		}
+
+		public String getName() {
+			return name;
+		}
+
+		public void setName(String name) {
+			this.name = name;
+		}
+
+		public Level2 getLevel2Parent() {
+			return level2Parent;
+		}
+
+		public void setLevel2Parent(Level2 level2Parent) {
+			this.level2Parent = level2Parent;
+		}
+	}
+}