HHH-16974 Add test for issue

Author: dreab8

hibernate-core/src/test/java/org/hibernate/orm/test/hql/QueryComparingAssociationToNullTest.java

@@ -0,0 +1,115 @@
+package org.hibernate.orm.test.hql;
+
+import java.time.LocalDate;
+
+import org.hibernate.dialect.DerbyDialect;
+
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.hibernate.testing.orm.junit.SkipForDialect;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Query;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+@DomainModel(
+		annotatedClasses = {
+				QueryComparingAssociationToNullTest.Parent.class,
+				QueryComparingAssociationToNullTest.Child.class,
+		}
+)
+@SessionFactory
+@JiraKey("HHH-16974")
+@SkipForDialect( dialectClass = DerbyDialect.class, reason = "it does not like `= null`")
+public class QueryComparingAssociationToNullTest {
+
+	@Test
+	public void testQuery(SessionFactoryScope scope) {
+		LocalDate date = LocalDate.now();
+		scope.inTransaction(
+				session -> {
+					Child child = new Child( 1, "first" );
+					Parent parent = new Parent( 1, date, child );
+					session.persist( child );
+					session.persist( parent );
+				}
+		);
+
+		scope.inTransaction(
+				session -> {
+					Query query = session.createQuery(
+							"SELECT p  FROM Parent p  WHERE p.child = NULL ",
+							Parent.class
+					);
+					query.getResultList();
+				}
+		);
+
+		scope.inTransaction(
+				session -> {
+					Query query = session.createQuery(
+							"SELECT p  FROM Parent p  WHERE p.child = NULL OR p.date = :date  ",
+							Parent.class
+					).setParameter( "date", date );
+					assertThat(query.getResultList().size()).isEqualTo( 1 );
+				}
+		);
+
+		scope.inTransaction(
+				session -> {
+					Query query = session.createQuery(
+							"SELECT p  FROM Parent p  WHERE p.child = NULL OR p.date = NULL  ",
+							Parent.class
+					);
+					query.getResultList();
+				}
+		);
+	}
+
+	@Entity(name = "Parent")
+	public static class Parent {
+
+		@Id
+		private Integer id;
+
+		@Column(name = "COLUMN_DATE")
+		private LocalDate date;
+
+		@ManyToOne
+		private Child child;
+
+
+		public Parent() {
+		}
+
+		public Parent(Integer id, LocalDate date, Child child) {
+			this.id = id;
+			this.date = date;
+			this.child = child;
+		}
+	}
+
+	@Entity(name = "Child")
+	public static class Child {
+		@Id
+		private Integer id;
+
+		private String name;
+
+		public Child() {
+		}
+
+		public Child(Integer id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+	}
+
+}