HHH-17178 Add test for issue

Author: mbellade

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

@@ -0,0 +1,145 @@
+/*
+ * 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.Collection;
+import java.util.HashSet;
+
+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.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import jakarta.persistence.Inheritance;
+import jakarta.persistence.InheritanceType;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.OneToMany;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Marco Belladelli
+ */
+@DomainModel( annotatedClasses = {
+		TreatedPluralJoinIsNullTest.MainEntity.class,
+		TreatedPluralJoinIsNullTest.ParentEntity.class,
+		TreatedPluralJoinIsNullTest.ChildEntity.class,
+} )
+@SessionFactory
+@Jira( "https://hibernate.atlassian.net/browse/HHH-17178" )
+public class TreatedPluralJoinIsNullTest {
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			session.persist( new MainEntity() );
+			final MainEntity main = new MainEntity();
+			final ChildEntity child = new ChildEntity( main, "test_child" );
+			session.persist( main );
+			session.persist( child );
+		} );
+	}
+
+	@AfterAll
+	public void tearDown(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			session.createMutationQuery( "delete from ParentEntity" ).executeUpdate();
+			session.createMutationQuery( "delete from MainEntity" ).executeUpdate();
+		} );
+	}
+
+	@Test
+	public void testIsNull(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final MainEntity result = session.createQuery(
+					"select m from MainEntity m left join treat(m.parents as ChildEntity) c where c is null",
+					MainEntity.class
+			).getSingleResult();
+			assertThat( result.getParents() ).isEmpty();
+		} );
+	}
+
+	@Test
+	public void testIsNotNull(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final MainEntity result = session.createQuery(
+					"select m from MainEntity m left join treat(m.parents as ChildEntity) c where c is not null",
+					MainEntity.class
+			).getSingleResult();
+			assertThat( result.getParents() ).hasSize( 1 );
+			final ParentEntity parent = result.getParents().iterator().next();
+			assertThat( parent ).isInstanceOf( ChildEntity.class );
+			assertThat( ( (ChildEntity) parent ).getData() ).isEqualTo( "test_child" );
+		} );
+	}
+
+	@Entity( name = "MainEntity" )
+	public static class MainEntity {
+		@Id
+		@GeneratedValue
+		private Long id;
+
+		@OneToMany( mappedBy = "main" )
+		private Collection<ParentEntity> parents = new HashSet<>();
+
+		public Long getId() {
+			return id;
+		}
+
+		public Collection<ParentEntity> getParents() {
+			return parents;
+		}
+	}
+
+	@Entity( name = "ParentEntity" )
+	@Inheritance( strategy = InheritanceType.JOINED )
+	public abstract static class ParentEntity {
+		@Id
+		@GeneratedValue
+		private Long id;
+
+		@ManyToOne
+		private MainEntity main;
+
+		public ParentEntity() {
+		}
+
+		public ParentEntity(MainEntity main) {
+			this.main = main;
+		}
+
+		public Long getId() {
+			return id;
+		}
+
+		public MainEntity getMain() {
+			return main;
+		}
+	}
+
+	@Entity( name = "ChildEntity" )
+	public static class ChildEntity extends ParentEntity {
+		private String data;
+
+		public ChildEntity() {
+		}
+
+		public ChildEntity(MainEntity main, String data) {
+			super( main );
+			this.data = data;
+		}
+
+		public String getData() {
+			return data;
+		}
+	}
+}