GNMI-1.11: Adding tolerance for incoming/outgoing packet delta equiva…

…lence check (openconfig#2401)

* GNMI-1.11: Removing incoming/outgoing packet delta equivalence check

When incoming and outgoing ports are in different linecards, the packet
counters for ongoing traffic in gnmi-subscription may have difference in
update duration.

Considering that gnmi-subscription update equivalence check
may not be valid on multiple linecard dut, thus removing it.

"This code is a Contribution to the OpenConfig Feature Profiles project ("Work") made under the Google Software Grant and Corporate Contributor License Agreement ("CLA") and governed by the Apache License 2.0. No other rights or licenses in or to any of Nokia's intellectual property are granted for any other purpose. This code is provided on an "as is" basis without any warranties of any kind."

* Instead of removing the check, adding tolerance as per discussion in b/315929197

feature/gnmi/otg_tests/telemetry_interface_packet_counters_test/telemetry_interface_packet_counters_test.go

@@ -205,14 +205,17 @@ func validateInAndOutPktsPerSecond(t *testing.T, dut *ondatra.DUTDevice, i1, i2
 		return pktCounterOK
 	}
 
+	var tolerance = uint64(70)
 	for i := 1; i < len(inPkts); i++ {
 		inValOld, _ := inPkts[i-1].Val()
 		outValOld, _ := outPkts[i-1].Val()
 		inValLatest, _ := inPkts[i].Val()
 		outValLatest, _ := outPkts[i].Val()
+		inValDelta := inValLatest - inValOld
+		outValDelta := outValLatest - outValOld
 		t.Logf("Incoming Packets: %d, Outgoing Packets: %d", inValLatest, outValLatest)
-		if inValLatest == inValOld || outValLatest == outValOld || (inValLatest-inValOld != outValLatest-outValOld) {
-			t.Logf("Comparison with previous iteration: Incoming Packets Delta : %d, Outgoing Packets Delta: %d", inValLatest-inValOld, outValLatest-outValOld)
+		if inValLatest == inValOld || outValLatest == outValOld || outValDelta <= inValDelta-tolerance || outValDelta >= inValDelta+tolerance {
+			t.Logf("Comparison with previous iteration: Incoming Packets Delta : %d, Outgoing Packets Delta: %d, Tolerance: %d", inValDelta, outValDelta, tolerance)
 			pktCounterOK = false
 			break
 		}