HHH-18679 Add test for issue

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/generated/GeneratedWritableIdTest.java

@@ -0,0 +1,80 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.mapping.generated;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import org.hibernate.annotations.ColumnDefault;
+import org.hibernate.annotations.Generated;
+import org.hibernate.dialect.H2Dialect;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.Jira;
+import org.hibernate.testing.orm.junit.RequiresDialect;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Marco Belladelli
+ */
+@DomainModel(annotatedClasses = GeneratedWritableIdTest.TestEntity.class)
+@SessionFactory
+@Jira("https://hibernate.atlassian.net/browse/HHH-18679")
+@RequiresDialect(H2Dialect.class)
+public class GeneratedWritableIdTest {
+	@Test
+	public void testDefaultId(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final TestEntity entity = new TestEntity( null, "entity_1" );
+			session.persist( entity );
+			session.flush();
+			assertThat( entity.getId() ).isEqualTo( 1L );
+		} );
+	}
+
+	@Test
+	public void testAssignedId(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final TestEntity entity = new TestEntity( 2L, "entity_2" );
+			session.persist( entity );
+			session.flush();
+			assertThat( entity.getId() ).isEqualTo( 2L );
+		} );
+	}
+
+	@AfterAll
+	public void tearDown(SessionFactoryScope scope) {
+		scope.getSessionFactory().getSchemaManager().truncateMappedObjects();
+	}
+
+	@Entity(name = "TestEntity")
+	static class TestEntity {
+		@Id
+		@Generated(writable = true)
+		@ColumnDefault("1")
+		private Long id;
+
+		private String name;
+
+		public TestEntity() {
+		}
+
+		public TestEntity(Long id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public Long getId() {
+			return id;
+		}
+
+		public String getName() {
+			return name;
+		}
+	}
+}