HHH-19515 add a test for the issue

Author: gavinking

hibernate-core/src/test/java/org/hibernate/orm/test/naming/PhysicalNamingTest.java

@@ -0,0 +1,54 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.naming;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import org.hibernate.boot.model.naming.CamelCaseToUnderscoresNamingStrategy;
+import org.hibernate.boot.model.naming.Identifier;
+import org.hibernate.cfg.MappingSettings;
+import org.hibernate.testing.orm.junit.EntityManagerFactoryScope;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.Jpa;
+import org.hibernate.testing.orm.junit.Setting;
+import org.junit.jupiter.api.Test;
+
+@Jpa(annotatedClasses = PhysicalNamingTest.TheEntity.class,
+	integrationSettings = @Setting(
+			name = MappingSettings.PHYSICAL_NAMING_STRATEGY,
+			value = "org.hibernate.orm.test.naming.PhysicalNamingTest$NamingStrategy"))
+public class PhysicalNamingTest {
+
+	public static class NamingStrategy
+			extends CamelCaseToUnderscoresNamingStrategy {
+		@Override
+		protected Identifier unquotedIdentifier(Identifier name) {
+			Identifier identifier = super.unquotedIdentifier( name );
+			return new Identifier( identifier.getText() + "_",
+					identifier.isQuoted() );
+		}
+	}
+
+
+	@JiraKey("HHH-19515")
+	@Test void test(EntityManagerFactoryScope scope) {
+		scope.inTransaction( em -> {
+			// make sure _ was not appended more than once
+			em.createNativeQuery(
+							"select its_id_, its_name_, its_friend_its_id_ from the_entity_",
+							Object[].class )
+					.getResultList();
+		});
+	}
+
+	@Entity(name = "TheEntity")
+	static class TheEntity {
+		@Id long itsId;
+		String itsName;
+		@ManyToOne
+		TheEntity itsFriend;
+	}
+}