HHH-8114 Add test for merging detached collection with removed element

hibernate-core/src/test/java/org/hibernate/orm/test/cascade/MergeCollectionWithRemovedElementTest.java

@@ -0,0 +1,159 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.cascade;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.OneToMany;
+import org.hibernate.Hibernate;
+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.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashSet;
+import java.util.Set;
+
+@DomainModel(
+		annotatedClasses = {
+				MergeCollectionWithRemovedElementTest.Parent.class,
+				MergeCollectionWithRemovedElementTest.Child.class,
+				MergeCollectionWithRemovedElementTest.GrandChild.class
+		}
+)
+@SessionFactory
+@Jira("https://hibernate.atlassian.net/browse/HHH-8114")
+public class MergeCollectionWithRemovedElementTest {
+
+	@BeforeEach
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					Parent p1 = new Parent( 1L, "p1" );
+					Child c1 = new Child( 2L );
+					Child c2 = new Child( 3L );
+					GrandChild gc1 = new GrandChild( 4L );
+					GrandChild gc2 = new GrandChild( 5L );
+					GrandChild gc3 = new GrandChild( 6L );
+					GrandChild gc4 = new GrandChild( 7L );
+					p1.addChild( c1 );
+					p1.addChild( c2 );
+					c1.addGrandChild( gc1 );
+					c1.addGrandChild( gc2 );
+					c2.addGrandChild( gc3 );
+					c2.addGrandChild( gc4 );
+					session.persist( p1 );
+					session.persist( gc1 );
+					session.persist( gc2 );
+					session.persist( gc3 );
+					session.persist( gc4 );
+				}
+		);
+	}
+
+	@AfterEach
+	public void tearDown(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					session.createQuery( "delete from GrandChild" ).executeUpdate();
+					session.createQuery( "delete from Child" ).executeUpdate();
+					session.createQuery( "delete from Parent" ).executeUpdate();
+				}
+		);
+	}
+
+	@Test
+	public void testMergeDetachedAfterFlush(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					// Load all data
+					Parent parent = session.find( Parent.class, 1L);
+					for ( Child u : parent.children ) {
+						Hibernate.initialize( u.grandChildren );
+					}
+					// Detach all data
+					session.clear();
+					// Load the parent into the PC
+					session.find( Parent.class, 1L);
+					// Remove a grand child and also remove it from the detached object
+					Child u = parent.children.iterator().next();
+					GrandChild grandChild = u.grandChildren.iterator().next();
+					session.remove( grandChild );
+					u.grandChildren.remove( grandChild );
+					// Flush the remove of the grand child
+					session.flush();
+					// Clear the PC
+					session.clear();
+					// Merge the detached object
+					session.merge( parent );
+				}
+		);
+	}
+
+	@Entity(name = "Parent")
+	public static class Parent {
+		@Id
+		Long id;
+		String name;
+		@OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, orphanRemoval = true)
+		Set<Child> children = new HashSet<>(0);
+
+		public Parent() {
+		}
+
+		public Parent(Long id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public void addChild(Child child) {
+			children.add(child);
+			child.parent = this;
+		}
+	}
+
+	@Entity(name = "Child")
+	public static class Child {
+		@Id
+		Long id;
+		@ManyToOne(fetch = FetchType.LAZY)
+		Parent parent;
+		@OneToMany(mappedBy = "child")
+		Set<GrandChild> grandChildren = new HashSet<>(0);
+
+		public Child() {
+		}
+
+		public Child(Long id) {
+			this.id = id;
+		}
+
+		public void addGrandChild(GrandChild grandChild) {
+			grandChildren.add(grandChild);
+			grandChild.child = this;
+		}
+	}
+
+	@Entity(name = "GrandChild")
+	public static class GrandChild {
+		@Id
+		Long id;
+		@ManyToOne(fetch = FetchType.LAZY)
+		Child child;
+
+		public GrandChild() {
+		}
+
+		public GrandChild(Long id) {
+			this.id = id;
+		}
+	}
+}