HHH-16438 - Add test for issue where left outer joins do not work with single table polymorphic entities because of the discriminator in the where clause

Signed-off-by: Jan Schatteman <jschatte@redhat.com>

hibernate-core/src/test/java/org/hibernate/orm/test/join/JoinWithSingleTableInheritanceTest.java

@@ -0,0 +1,144 @@
+/*
+ * 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.join;
+
+import java.util.List;
+
+import jakarta.persistence.DiscriminatorColumn;
+import jakarta.persistence.DiscriminatorType;
+import jakarta.persistence.DiscriminatorValue;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+/**
+ * @author Jan Schatteman
+ */
+@TestForIssue( jiraKey = "HHH-16435")
+@DomainModel(
+		annotatedClasses = {
+				JoinWithSingleTableInheritanceTest.AbstractSuperClass.class,
+				JoinWithSingleTableInheritanceTest.ChildEntityA.class,
+				JoinWithSingleTableInheritanceTest.ChildEntityB.class,
+				JoinWithSingleTableInheritanceTest.RootOne.class
+		}
+)
+@SessionFactory
+public class JoinWithSingleTableInheritanceTest {
+
+	@AfterEach
+	public void cleanup( SessionFactoryScope scope ) {
+		scope.inTransaction(
+				s -> {
+					s.createMutationQuery( "delete from AbstractSuperClass" ).executeUpdate();
+					s.createMutationQuery( "delete from RootOne" ).executeUpdate();
+				}
+		);
+	}
+
+	@Test
+	public void testLeftJoinOnSingleTableInheritance(SessionFactoryScope scope) {
+		scope.inTransaction(
+				s -> s.persist( new RootOne() )
+		);
+
+		scope.inTransaction(
+				s -> {
+					List<RootOne> l = s.createSelectionQuery( "select r from RootOne r left join ChildEntityA ce on ce.id = r.someOtherId", RootOne.class ).list();
+					assertEquals( 1, l.size() );
+				}
+		);
+	}
+
+	@Test
+	public void testLeftJoinOnSingleTableInheritance2(SessionFactoryScope scope) {
+		scope.inTransaction(
+				s -> {
+					s.persist(new ChildEntityA( 11 ));
+					s.persist(new ChildEntityB( 21 ));
+					RootOne r1 = new RootOne();
+					r1.setSomeOtherId( 11 );
+					s.persist( r1 );
+					RootOne r2 = new RootOne();
+					r2.setSomeOtherId( 21 );
+					s.persist( r2 );
+				}
+		);
+
+		scope.inTransaction(
+				s -> {
+					List<Object[]> l = s.createSelectionQuery( "select r.id, r.someOtherId, ce.id from RootOne r left join ChildEntityA ce on ce.id = r.someOtherId order by r.id", Object[].class ).list();
+					assertEquals( 2, l.size() );
+					Object[] r1 = l.get( 0 );
+					assertEquals( (int) r1[0], 1 );
+					assertEquals( (int) r1[1], 11 );
+					assertEquals( (int) r1[2], 11 );
+					// r2 has to be there, but shouldn't have any data w/ respect to ChildEntityB
+					Object[] r2 = l.get( 1 );
+					assertEquals( (int) r2[0], 2 );
+					assertEquals( (int) r2[1], 21 );
+					assertNull( r2[2] );
+
+				}
+		);
+	}
+
+	@Entity(name = "AbstractSuperClass")
+	@DiscriminatorColumn(name = "DISC_COL", discriminatorType = DiscriminatorType.INTEGER)
+	public static abstract class AbstractSuperClass {
+		@Id
+		private Integer id;
+
+		public AbstractSuperClass(Integer id) {
+			this.id = id;
+		}
+	}
+
+	@Entity(name = "ChildEntityA")
+	@DiscriminatorValue("1")
+	public static class ChildEntityA extends AbstractSuperClass {
+		public ChildEntityA(Integer id) {
+			super( id );
+		}
+	}
+
+	@Entity(name = "ChildEntityB")
+	@DiscriminatorValue("2")
+	public static class ChildEntityB extends AbstractSuperClass {
+		public ChildEntityB(Integer id) {
+			super( id );
+		}
+	}
+
+	@Entity(name = "RootOne")
+	public static class RootOne {
+		@Id
+		@GeneratedValue
+		Integer id;
+		Integer someOtherId;
+
+		public Integer getSomeOtherId() {
+			return someOtherId;
+		}
+
+		public void setSomeOtherId(Integer someOtherId) {
+			this.someOtherId = someOtherId;
+		}
+	}
+
+}