Fix retry ack handling in DownStreamMsgContext and add tests

Author: nagarjunahp88-byte

eventmesh-runtime/src/main/java/org/apache/eventmesh/runtime/core/protocol/tcp/client/session/push/DownStreamMsgContext.java

@@ -185,14 +185,36 @@ private boolean isRetryMsgTimeout(DownStreamMsgContext downStreamMsgContext) {
      *
      * @param downStreamMsgContext Down Stream Message Context
      */
-    private void eventMeshAckMsg(DownStreamMsgContext downStreamMsgContext) {
-        List<CloudEvent> msgExts = new ArrayList<>();
-        msgExts.add(downStreamMsgContext.event);
-        log.warn("eventMeshAckMsg topic:{}, seq:{}, bizSeq:{}", downStreamMsgContext.event.getSubject(),
-            downStreamMsgContext.seq, downStreamMsgContext.event.getExtension(EventMeshConstants.PROPERTY_MESSAGE_KEYS));
-        downStreamMsgContext.consumer.updateOffset(msgExts, downStreamMsgContext.consumeConcurrentlyContext);
+   private void eventMeshAckMsg(DownStreamMsgContext downStreamMsgContext) {
+    if (downStreamMsgContext.consumer == null
+        || downStreamMsgContext.consumeConcurrentlyContext == null
+        || downStreamMsgContext.event == null) {
+
+        log.warn(
+            "eventMeshAckMsg skipped, consumer:{}, context:{}, event:{}",
+            downStreamMsgContext.consumer == null,
+            downStreamMsgContext.consumeConcurrentlyContext == null,
+            downStreamMsgContext.event == null
+        );
+        return;
     }
 
+    List<CloudEvent> msgExts = new ArrayList<>();
+    msgExts.add(downStreamMsgContext.event);
+
+    log.warn(
+        "eventMeshAckMsg topic:{}, seq:{}, bizSeq:{}",
+        downStreamMsgContext.event.getSubject(),
+        downStreamMsgContext.seq,
+        downStreamMsgContext.event.getExtension(EventMeshConstants.PROPERTY_MESSAGE_KEYS)
+    );
+
+    downStreamMsgContext.consumer.updateOffset(
+        msgExts,
+        downStreamMsgContext.consumeConcurrentlyContext
+    );
+}
+
     @Override
     public void doRun() {
         retry();

eventmesh-runtime/src/test/java/org/apache/eventmesh/runtime/core/protocol/tcp/client/session/push/DownStreamMSGContextTest.java

@@ -0,0 +1,73 @@
+package org.apache.eventmesh.runtime.core.protocol.tcp.client.session.push;
+
+import org.apache.eventmesh.api.AbstractContext;
+import org.apache.eventmesh.common.protocol.SubscriptionItem;
+import org.apache.eventmesh.common.protocol.SubscriptionMode;
+import org.apache.eventmesh.runtime.core.plugin.MQConsumerWrapper;
+import org.apache.eventmesh.runtime.core.protocol.tcp.client.session.Session;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+
+import org.junit.jupiter.api.Test;
+
+import java.net.URI;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+class DownStreamMsgContextTest {
+
+    private CloudEvent buildEvent() {
+        return CloudEventBuilder.v1()
+            .withId("test-id")
+            .withSource(URI.create("test://source"))
+            .withType("test-type")
+            .withSubject("test-topic")
+            .build();
+    }
+
+    private SubscriptionItem buildSubscriptionItem() {
+        SubscriptionItem item = new SubscriptionItem();
+        item.setMode(SubscriptionMode.CLUSTERING);
+        return item;
+    }
+
+    @Test
+    void retry_shouldNotThrowException_whenConsumerOrContextIsNull() {
+
+        CloudEvent event = buildEvent();
+
+        // Intentionally set to null to simulate edge case
+        Session session = null;
+        MQConsumerWrapper consumer = null;
+        AbstractContext context = null;
+
+        DownStreamMsgContext msgContext = new DownStreamMsgContext(
+            event,
+            session,
+            consumer,
+            context,
+            false,
+            buildSubscriptionItem()
+        );
+
+        assertDoesNotThrow(msgContext::retry);
+    }
+
+    @Test
+    void ackMsg_shouldNotThrowException_whenDependenciesAreNull() {
+
+        CloudEvent event = buildEvent();
+
+        DownStreamMsgContext msgContext = new DownStreamMsgContext(
+            event,
+            null,
+            null,
+            null,
+            false,
+            buildSubscriptionItem()
+        );
+
+        assertDoesNotThrow(msgContext::ackMsg);
+    }
+}