test(incarnation-sapere): harden LsaNode concurrency test

alchemist-incarnation-sapere/src/test/java/it/unibo/alchemist/model/sapere/nodes/LsaNodeConcurrencyTest.java

@@ -18,13 +18,16 @@
 import it.unibo.alchemist.model.positions.Euclidean2DPosition;
 import org.junit.jupiter.api.Test;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.TimeoutException;
 
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -52,11 +55,11 @@ void testConcurrentGetContentsAndModification() throws InterruptedException {
         final int numberOfOperations = 100;
         final ExecutorService executor = Executors.newFixedThreadPool(numberOfThreads);
         final CountDownLatch latch = new CountDownLatch(numberOfThreads);
-        final AtomicBoolean exceptionOccurred = new AtomicBoolean(false);
+        final List<Future<?>> tasks = new ArrayList<>(numberOfThreads);
         // Start threads that modify the node while others read from it
         for (int i = 0; i < numberOfThreads; i++) {
             final int threadId = i;
-            executor.submit(() -> {
+            tasks.add(executor.submit(() -> {
                 try {
                     for (int j = 0; j < numberOfOperations; j++) {
                         if (threadId % 2 == 0) {
@@ -69,7 +72,7 @@ void testConcurrentGetContentsAndModification() throws InterruptedException {
                             assertNotNull(lsaSpace);
                         } else {
                             // Writer threads
-                            final ILsaMolecule newMolecule = new LsaMolecule("thread" + threadId + "_" + j);
+                            final ILsaMolecule newMolecule = new LsaMolecule("thread" + threadId + "x" + j);
                             node.setConcentration(newMolecule);
                             // Sometimes remove molecules to simulate real concurrent modification
                             if (j % 10 == 0 && node.getMoleculeCount() > MIN_MOLECULES) {
@@ -81,19 +84,57 @@ void testConcurrentGetContentsAndModification() throws InterruptedException {
                             }
                         }
                     }
-                } catch (final IllegalStateException | java.util.ConcurrentModificationException e) {
-                    exceptionOccurred.set(true);
-                    e.printStackTrace();
                 } finally {
                     latch.countDown();
                 }
-            });
+                return null;
+            }));
         }
         // Wait for all threads to complete
-        assertTrue(latch.await(TIMEOUT_SECONDS, TimeUnit.SECONDS), "Test should complete within 30 seconds");
-        executor.shutdown();
-        // No exceptions should have occurred (especially no ConcurrentModificationException)
-        assertFalse(exceptionOccurred.get(), "No exceptions should occur during concurrent access");
+        AssertionError primaryFailure = null;
+        try {
+            assertTrue(latch.await(TIMEOUT_SECONDS, TimeUnit.SECONDS), "Test should complete within " + TIMEOUT_SECONDS + " seconds");
+            for (final Future<?> task : tasks) {
+                try {
+                    task.get(TIMEOUT_SECONDS, TimeUnit.SECONDS);
+                } catch (final InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                    throw new AssertionError("Test interrupted while waiting for task", e);
+                } catch (final ExecutionException e) {
+                    throw new AssertionError("Task failed with exception", e.getCause());
+                } catch (final TimeoutException e) {
+                    task.cancel(true);
+                    throw new AssertionError("Task timed out after " + TIMEOUT_SECONDS + " seconds", e);
+                }
+            }
+        } catch (final AssertionError e) {
+            primaryFailure = e;
+        } finally {
+            executor.shutdownNow();
+            try {
+                if (!executor.awaitTermination(TIMEOUT_SECONDS, TimeUnit.SECONDS)) {
+                    final AssertionError terminationError = new AssertionError(
+                        "Executor did not terminate within " + TIMEOUT_SECONDS + " seconds");
+                    if (primaryFailure != null) {
+                        primaryFailure.addSuppressed(terminationError);
+                    } else {
+                        throw terminationError;
+                    }
+                }
+            } catch (final InterruptedException e) {
+                Thread.currentThread().interrupt();
+                final AssertionError terminationError = new AssertionError(
+                    "Interrupted while waiting for executor termination", e);
+                if (primaryFailure != null) {
+                    primaryFailure.addSuppressed(terminationError);
+                } else {
+                    throw terminationError;
+                }
+            }
+        }
+        if (primaryFailure != null) {
+            throw primaryFailure;
+        }
         // Verify the node is still in a valid state
         final Map<Molecule, List<ILsaMolecule>> finalContents = node.getContents();
         assertNotNull(finalContents);