add test case for cli show pfcwd stat (sonic-net#14711)

What is the motivation for this PR?
sonic-net#11169

How did you do it?
Add a new test case to cover "pfcwd show stats" cmd

Trigger PFC storm with action drop or forward
send_tx_egress and send_rx_ingress
execute CMD 'show pfcwd stat' and ensure the output is expected
How did you verify/test it?
https://elastictest.org/scheduler/testplan/66f268ae4216a91fd43d97b6
https://elastictest.org/scheduler/testplan/66f268880369ccd340b3ea60

tests/common/helpers/pfcwd_helper.py

@@ -567,15 +567,60 @@ def has_neighbor_device(setup_pfc_test):
     return True
 
 
-def check_pfc_storm_state(dut, port, queue):
+def check_pfc_storm_state(dut, port, queue, expected_state):
     """
     Helper function to check if PFC storm is detected/restored on a given queue
     """
-    pfcwd_stats = dut.show_and_parse("show pfcwd stats")
-    queue_name = str(port) + ":" + str(queue)
-    for entry in pfcwd_stats:
-        if entry["queue"] == queue_name:
-            logger.info("PFCWD status on queue {} stats: {}".format(queue_name, entry))
-            return entry['storm detected/restored']
-    logger.info("PFCWD not triggered on queue {}".format(queue_name))
-    return None
+    pfcwd_stat = parser_show_pfcwd_stat(dut, port, queue)
+    if expected_state == "storm":
+        if ("storm" in pfcwd_stat[0]['status']) and \
+                int(pfcwd_stat[0]['storm_detect_count']) > int(pfcwd_stat[0]['restored_count']):
+            return True
+    else:
+        if ("storm" not in pfcwd_stat[0]['status']) and \
+                int(pfcwd_stat[0]['storm_detect_count']) == int(pfcwd_stat[0]['restored_count']):
+            return True
+    return False
+
+
+def parser_show_pfcwd_stat(dut, select_port, select_queue):
+    """
+    CLI "show pfcwd stats" output:
+    admin@bjw-can-7060-1:~$ show pfcwd stats
+            QUEUE    STATUS    STORM DETECTED/RESTORED    TX OK/DROP    RX OK/DROP    TX LAST OK/DROP    RX LAST OK/DROP # noqa: E501
+    -------------  --------  -------------------------  ------------  ------------  -----------------  ----------------- # noqa: E501
+    Ethernet112:4       N/A                        2/2       100/100       100/100              100/0              100/0 # noqa: E501
+    admin@bjw-can-7060-1:~$
+    """
+    logger.info("port {} queue {}".format(select_port, select_queue))
+    pfcwd_stat_output = dut.show_and_parse('show pfcwd stat')
+
+    pfcwd_stat = []
+    for item in pfcwd_stat_output:
+        port, queue = item['queue'].split(':')
+        if port != select_port or int(queue) != int(select_queue):
+            continue
+        storm_detect_count, restored_count = item['storm detected/restored'].split('/')
+        tx_ok_count, tx_drop_count = item['tx ok/drop'].split('/')
+        rx_ok_count, rx_drop_count = item['rx ok/drop'].split('/')
+        tx_last_ok_count, tx_last_drop_count = item['tx last ok/drop'].split('/')
+        rx_last_ok_count, rx_last_drop_count = item['rx last ok/drop'].split('/')
+
+        parsed_dict = {
+            'port': port,
+            'queue': queue,
+            'status': item['status'],
+            'storm_detect_count': storm_detect_count,
+            'restored_count': restored_count,
+            'tx_ok_count': tx_ok_count,
+            'tx_drop_count': tx_drop_count,
+            'rx_ok_count': rx_ok_count,
+            'rx_drop_count': rx_drop_count,
+            'tx_last_ok_count': tx_last_ok_count,
+            'tx_last_drop_count': tx_last_drop_count,
+            'rx_last_ok_count': rx_last_ok_count,
+            'rx_last_drop_count': rx_last_drop_count
+        }
+        pfcwd_stat.append(parsed_dict)
+
+    return pfcwd_stat