Add test case for handling consumername == NULL case in xpending (#2451)

Author: dengliming

src/main/java/redis/clients/jedis/Jedis.java

@@ -4254,9 +4254,6 @@ public List<StreamPendingEntry> xpending(final String key, final String groupnam
       final StreamEntryID start, final StreamEntryID end, final int count, final String consumername) {
     checkIsInMultiOrPipeline();
     client.xpending(key, groupname, start, end, count, consumername);
-
-    // TODO handle consumername == NULL case
-
     return BuilderFactory.STREAM_PENDING_ENTRY_LIST.build(client.getObjectMultiBulkReply());
   }
 

src/test/java/redis/clients/jedis/tests/commands/StreamsCommandsTest.java

@@ -195,7 +195,7 @@ public void xreadWithParams() {
     assertEquals(1, streams1.get(0).getValue().size());
     assertEquals(id1, streams1.get(0).getValue().get(0).getID());
     assertEquals(map, streams1.get(0).getValue().get(0).getFields());
-    
+
     assertNull(jedis.xread(XReadParams.xReadParams().block(1), Collections.singletonMap("xread-stream1", id1)));
     assertNull(jedis.xread(XReadParams.xReadParams(), Collections.singletonMap("xread-stream1", id1)));
 
@@ -444,6 +444,13 @@ public void xpendeing() {
     assertEquals(1, pendingRange.get(0).getDeliveredTimes());
     assertEquals("xpendeing-consumer", pendingRange.get(0).getConsumerName());
 
+    // Without consumer
+    pendingRange = jedis.xpending("xpendeing-stream", "xpendeing-group", null, null, 3, null);
+    assertEquals(1, pendingRange.size());
+    assertEquals(id1, pendingRange.get(0).getID());
+    assertEquals(1, pendingRange.get(0).getDeliveredTimes());
+    assertEquals("xpendeing-consumer", pendingRange.get(0).getConsumerName());
+
     // Sleep for 1000ms so we can claim events pending for more than 500ms
     try {
       Thread.sleep(1000);