[#2640] Update CancelSignalTest

I don't know if this test actually makes sense:
the cancel opertion happens in a different thread that causes
some error when calling session.close because the thread doesn't match
the one the session was open.

I'm going to keep it because it was introduced to solve #1436
but we might need to review it again in the future.

Author: DavideD

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

@@ -5,16 +5,19 @@
  */
 package org.hibernate.reactive;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Objects;
 import java.util.Queue;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionStage;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
-import java.util.stream.IntStream;
+
+
 
 import org.junit.jupiter.api.Test;
 
@@ -27,73 +30,76 @@
 import jakarta.persistence.Id;
 import jakarta.persistence.Table;
 
-import static java.util.Arrays.stream;
 import static java.util.concurrent.CompletableFuture.allOf;
 import static java.util.concurrent.CompletableFuture.runAsync;
-import static java.util.stream.Stream.concat;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.hibernate.reactive.util.impl.CompletionStages.voidFuture;
 
 public class CancelSignalTest extends BaseReactiveTest {
 	private static final Logger LOG = Logger.getLogger( CancelSignalTest.class );
 
+	private static final int EXECUTION_SIZE = 10;
+
 	@Override
 	protected Collection<Class<?>> annotatedEntities() {
 		return List.of( GuineaPig.class );
 	}
 
+	@Override
+	public CompletionStage<Void> deleteEntities(Class<?>... entities) {
+		// We don't need to delete anything
+		return voidFuture();
+	}
+
 	@Test
 	public void cleanupConnectionWhenCancelSignal(VertxTestContext context) {
 		// larger than 'sql pool size' to check entering the 'pool waiting queue'
-		int executeSize = 10;
 		CountDownLatch firstSessionWaiter = new CountDownLatch( 1 );
 		Queue<Cancellable> cancellableQueue = new ConcurrentLinkedQueue<>();
 
-		ExecutorService withSessionExecutor = Executors.newFixedThreadPool( executeSize );
-		// Create some jobs that are going to be cancelled asynchronously
-		CompletableFuture[] withSessionFutures = IntStream
-				.range( 0, executeSize )
-				.mapToObj( i -> runAsync(
-						() -> {
-							CountDownLatch countDownLatch = new CountDownLatch( 1 );
-							Cancellable cancellable = getMutinySessionFactory()
-									.withSession( s -> {
-										LOG.debug( "start withSession: " + i );
-										sleep( 100 );
-										firstSessionWaiter.countDown();
-										return s.find( GuineaPig.class, 1 );
-									} )
-									.onTermination().invoke( () -> {
-										countDownLatch.countDown();
-										LOG.debug( "future " + i + " terminated" );
-									} )
-									.subscribe().with( item -> LOG.debug( "end withSession: "  + i  ) );
-							cancellableQueue.add( cancellable );
-							await( countDownLatch );
-						},
-						withSessionExecutor
-				) )
-				.toArray( CompletableFuture[]::new );
-
-		// Create jobs that are going to cancel the previous ones
-		ExecutorService cancelExecutor = Executors.newFixedThreadPool( executeSize );
-		CompletableFuture[] cancelFutures = IntStream
-				.range( 0, executeSize )
-				.mapToObj( i -> runAsync(
-						() -> {
-							await( firstSessionWaiter );
-							cancellableQueue.poll().cancel();
-							sleep( 500 );
-						},
-						cancelExecutor
-				) )
-				.toArray( CompletableFuture[]::new );
-
-		CompletableFuture<Void> allFutures = allOf( concat( stream( withSessionFutures ), stream( cancelFutures ) )
-						.toArray( CompletableFuture[]::new )
-		);
+		final List<CompletableFuture<?>> allFutures = new ArrayList<>();
+
+		ExecutorService withSessionExecutor = Executors.newFixedThreadPool( EXECUTION_SIZE );
+		for ( int j = 0; j < EXECUTION_SIZE; j++ ) {
+			final int i = j;
+			allFutures.add( runAsync( () -> {
+						  CountDownLatch countDownLatch = new CountDownLatch( 1 );
+						  Cancellable cancellable = getMutinySessionFactory()
+								  .withSession( s -> {
+									  LOG.info( "start withSession: " + i );
+									  sleep( 100 );
+									  firstSessionWaiter.countDown();
+									  return s.find( GuineaPig.class, 1 );
+								  } )
+								  .onCancellation().invoke( () -> {
+									  LOG.info( "future " + i + " cancelled" );
+									  countDownLatch.countDown();
+								  } )
+								  .subscribe()
+								  // We cancelled the job, it shouldn't really finish
+								  .with( item -> LOG.info( "end withSession: "  + i  ) );
+						  cancellableQueue.add( cancellable );
+						  await( countDownLatch );
+					  },
+					  withSessionExecutor
+			) );
+		}
 
-		// Test that there shouldn't be any pending process
-		test( context, allFutures.thenAccept( x -> assertThat( sqlPendingMetric() ).isEqualTo( 0.0 ) ) );
+		ExecutorService cancelExecutor = Executors.newFixedThreadPool( EXECUTION_SIZE );
+		for ( int i = 0; i < EXECUTION_SIZE; i++ ) {
+			allFutures.add( runAsync( () -> {
+						  await( firstSessionWaiter );
+						  cancellableQueue.poll().cancel();
+						  sleep( 500 );
+					  },
+					  cancelExecutor
+			) );
+		}
+
+		test(
+				context, allOf( allFutures.toArray( new CompletableFuture<?>[0] ) )
+						.thenAccept( x -> assertThat( sqlPendingMetric() ).isEqualTo( 0.0 ) )
+		);
 	}
 
 	private static double sqlPendingMetric() {