HHH-15622 Add test for issue

hibernate-core/src/test/java/org/hibernate/orm/test/entitygraph/DiscriminatorColumnFetchGraphTest.java

@@ -0,0 +1,139 @@
+package org.hibernate.orm.test.entitygraph;
+
+import java.util.List;
+import java.util.UUID;
+
+import org.hibernate.Hibernate;
+import org.hibernate.jpa.SpecHints;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.orm.junit.EntityManagerFactoryScope;
+import org.hibernate.testing.orm.junit.Jpa;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.DiscriminatorColumn;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import jakarta.persistence.Inheritance;
+import jakarta.persistence.InheritanceType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.MapsId;
+import jakarta.persistence.NamedAttributeNode;
+import jakarta.persistence.NamedEntityGraph;
+import jakarta.persistence.OneToOne;
+import jakarta.persistence.criteria.CriteriaBuilder;
+import jakarta.persistence.criteria.CriteriaQuery;
+import jakarta.persistence.criteria.Root;
+
+import static jakarta.persistence.GenerationType.AUTO;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+@Jpa(
+		annotatedClasses = {
+				DiscriminatorColumnFetchGraphTest.Dog.class,
+				DiscriminatorColumnFetchGraphTest.Animal.class,
+				DiscriminatorColumnFetchGraphTest.Behaviour.class
+		}
+)
+@TestForIssue(jiraKey = "HHH-15622")
+public class DiscriminatorColumnFetchGraphTest {
+
+	@BeforeEach
+	public void setUp(EntityManagerFactoryScope scope) {
+		scope.inTransaction(
+				entityManager -> {
+					Behaviour behaviour = new Behaviour();
+					entityManager.persist( behaviour );
+
+					Dog dog = new Dog( behaviour, 10 );
+					entityManager.persist( dog );
+				}
+		);
+	}
+
+	@Test
+	public void fetchGraphTest(EntityManagerFactoryScope scope) {
+		scope.inTransaction(
+				entityManager -> {
+					CriteriaBuilder cb = entityManager.getCriteriaBuilder();
+					CriteriaQuery<Behaviour> query = cb.createQuery( Behaviour.class );
+
+					Root<Behaviour> behaviourRoot = query.from( Behaviour.class );
+
+					List<Behaviour> behaviours = entityManager.createQuery( query.select( behaviourRoot ) )
+							.setHint(
+									SpecHints.HINT_SPEC_FETCH_GRAPH,
+									entityManager.getEntityGraph( "Behaviour.animal" )
+							)
+							.getResultList();
+					assertThat( behaviours.size() ).isEqualTo( 1 );
+					Behaviour behaviour = behaviours.get( 0 );
+					assertThat( Hibernate.isPropertyInitialized( behaviour, "animal" ) );
+				}
+		);
+	}
+
+	@Entity(name = "Animal")
+	@DiscriminatorColumn
+	@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
+	public static abstract class Animal {
+
+		@Id
+		@GeneratedValue(strategy = AUTO)
+		private UUID id;
+
+		@MapsId
+		@OneToOne(fetch = FetchType.LAZY, optional = false)
+		@JoinColumn(name = "behaviour_id", nullable = false, updatable = false)
+		private Behaviour behaviour;
+
+		protected Animal() {
+		}
+
+		public Animal(Behaviour behaviour) {
+			this.behaviour = behaviour;
+			behaviour.setAnimal( this );
+		}
+	}
+
+	@Entity(name = "Dog")
+	public static class Dog extends Animal {
+
+		protected Dog() {
+		}
+
+		public Dog(Behaviour behaviour, Integer age) {
+			super( behaviour );
+			this.age = age;
+		}
+
+		private Integer age;
+	}
+
+	@NamedEntityGraph(
+			name = "Behaviour.animal",
+			attributeNodes = @NamedAttributeNode("animal")
+	)
+	@Entity(name = "Behaviour")
+	public static class Behaviour {
+
+		@Id
+		@GeneratedValue(strategy = AUTO)
+		private UUID id;
+
+		@OneToOne(mappedBy = "behaviour", fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
+		private Animal animal;
+
+		public Behaviour() {
+		}
+
+		public void setAnimal(Animal animal) {
+			this.animal = animal;
+		}
+	}
+
+}