HHH-15045 Add test for issue

Author: dreab8

hibernate-core/src/test/java/org/hibernate/orm/test/onetoone/flush/DirtyFlushTest.java

@@ -0,0 +1,110 @@
+/*
+ * 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.onetoone.flush;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.orm.junit.EntityManagerFactoryScope;
+import org.hibernate.testing.orm.junit.Jpa;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.OneToOne;
+import jakarta.persistence.Table;
+import jakarta.persistence.Version;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@TestForIssue(jiraKey = "HHH-15045")
+@Jpa(
+		annotatedClasses = {
+				DirtyFlushTest.User.class,
+				DirtyFlushTest.Profile.class
+		}
+)
+public class DirtyFlushTest {
+
+	@BeforeEach
+	public void setUp(EntityManagerFactoryScope scope) {
+		scope.inTransaction( em -> {
+			final User user = new User();
+			user.id = 1;
+			user.version = 1;
+
+			final Profile profile = new Profile();
+			profile.id = 1;
+			profile.version = 1;
+
+			em.persist( user );
+			em.persist( profile );
+		} );
+	}
+
+	@Test
+	public void testDirtyFlushNotHappened(EntityManagerFactoryScope scope) {
+		scope.inTransaction( em -> {
+			final User user = em.find( User.class, 1 );
+			assertEquals( 1, user.version );
+
+			final Profile profile = em.find( Profile.class, 1 );
+			assertEquals( 1, profile.version );
+
+			profile.user = user;
+			user.profile = profile;
+
+			em.persist( profile );
+			em.flush();
+		} );
+
+		scope.inTransaction( em -> {
+			final Profile profile = em.find( Profile.class, 1 );
+			assertEquals( 2, profile.version );
+
+			final User user = em.find( User.class, 1 );
+			assertEquals(
+					1,
+					user.version,
+					"without fixing, the version will be bumped due to erroneous dirty flushing"
+					);
+		} );
+	}
+
+	@AfterEach
+	public void tearDown(EntityManagerFactoryScope scope) {
+		scope.inTransaction( em -> {
+			em.createQuery( "delete from Profile" ).executeUpdate();
+			em.createQuery( "delete from User" ).executeUpdate();
+		} );
+	}
+
+	@Entity(name = "User")
+	@Table(name = "USER_TABLE")
+	public static class User {
+		@Id
+		int id;
+
+		@Version
+		int version;
+
+		@OneToOne(mappedBy = "user")
+		Profile profile;
+	}
+
+	@Entity(name = "Profile")
+	@Table(name = "PROFILE_TABLE")
+	public static class Profile {
+		@Id
+		int id;
+
+		@Version
+		int version;
+		@OneToOne // internally Hibernate will use `@ManyToOne` for this field
+		User user;
+	}
+}