Examine the tx counters in WRRtest instead of counting what arrives a…

…t PTF

This test causes a burst of traffic to be transmitted by the DUT, but the
intervening network between the DUT and PTF may not be capable of handling the
entire burst of packets at full linerate.  Instead inspect the packet transmit
counters on the appropriate interface to ensure that at least the correct number
of packets were transmitted, and ensure that at least 1 of the packets are
observed at PTF.

tests/saitests/py3/sai_qos_tests.py

@@ -3878,8 +3878,12 @@ def runTest(self):
                        queue_counters_base)), file=sys.stderr)
 
         print([q_cnt_sum, total_pkts], file=sys.stderr)
-        # All packets sent should be received intact
-        assert (q_cnt_sum == total_pkts)
+
+        txPacketCount = port_counters[TRANSMITTED_OCTETS] - port_counters_base[TRANSMITTED_OCTETS]
+        # At least the correct number of packets must have been transmitted
+        assert (q_cnt_sum <= txPacketCount)
+        # And at least one of the valid packets has arrived at PTF
+        assert (total_pkts > 1)
 
 
 class LossyQueueTest(sai_base_test.ThriftInterfaceDataPlane):