Fix Db2 native query

Author: DavideD

hibernate-reactive-core/src/test/java/org/hibernate/reactive/NoEntitiesTest.java

@@ -11,6 +11,8 @@
 import io.vertx.junit5.VertxTestContext;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.hibernate.reactive.containers.DatabaseConfiguration.DBType.DB2;
+import static org.hibernate.reactive.containers.DatabaseConfiguration.dbType;
 
 public class NoEntitiesTest extends BaseReactiveTest {
 
@@ -23,7 +25,7 @@ public void emptyMetamodelWithMutiny() {
 	public void shouldBeAbleToRunQueryWithMutinyTransaction(VertxTestContext context) {
 		test( context, getMutinySessionFactory()
 				.withTransaction( s -> s
-						.createNativeQuery( "select 42", Long.class ).getSingleResult()
+						.createNativeQuery( selectQuery( 42 ), Long.class ).getSingleResult()
 				).invoke( result -> assertThat( result ).isEqualTo( 42L ) )
 		);
 	}
@@ -34,18 +36,24 @@ public void runNativeQueryWithMutinyTransactionAndFlush(VertxTestContext context
 				.withTransaction( s -> {
 					s.setFlushMode( FlushMode.ALWAYS );
 					return s
-							.createNativeQuery( "select 42", Long.class ).getSingleResult()
+							.createNativeQuery( selectQuery( 42 ), Long.class ).getSingleResult()
 							.call( s::flush );
 				} ).invoke( result -> assertThat( result ).isEqualTo( 42L ) )
 		);
 	}
 
+	private static String selectQuery(int value) {
+		return dbType() == DB2
+				? "values " + value
+				: "select " + value;
+	}
+
 	@Test
 	public void runStatelessNativeQueryWithMutinyTransactionAndFlush(VertxTestContext context) {
 		test(
 				context, getMutinySessionFactory()
 						.withStatelessTransaction( s -> s
-								.createNativeQuery( "select 42", Long.class )
+								.createNativeQuery( selectQuery( 42 ), Long.class )
 								.getSingleResult()
 						)
 						.invoke( result -> assertThat( result ).isEqualTo( 42L ) )
@@ -56,7 +64,7 @@ context, getMutinySessionFactory()
 	public void shouldBeAbleToRunQueryWithMutinyWithoutTransaction(VertxTestContext context) {
 		test( context, getMutinySessionFactory()
 				.openSession().chain( s -> s
-						.createNativeQuery( "select 666", Long.class ).getSingleResult()
+						.createNativeQuery( selectQuery( 666 ), Long.class ).getSingleResult()
 				).invoke( result -> assertThat( result ).isEqualTo( 666L ) )
 		);
 	}