Integrate the reproducer from William into tc-testing and use scapy
to generate packets for testing:

 # ./tdc.py -e 1676
  -- ns/SubPlugin.__init__
  -- scapy/SubPlugin.__init__
 Test 1676: NETEM nested duplicate 100%
 [ 1154.071135] v0p0id1676: entered promiscuous mode
 [ 1154.101066] virtio_net virtio0 enp1s0: entered promiscuous mode
 [ 1154.146301] virtio_net virtio0 enp1s0: left promiscuous mode
 .
 Sent 1 packets.
 [ 1154.173695] v0p0id1676: left promiscuous mode
 [ 1154.216159] v0p0id1676: entered promiscuous mode
 .
 Sent 1 packets.
 [ 1154.238398] v0p0id1676: left promiscuous mode
 [ 1154.260909] v0p0id1676: entered promiscuous mode
 .
 Sent 1 packets.
 [ 1154.282708] v0p0id1676: left promiscuous mode
 [ 1154.309399] v0p0id1676: entered promiscuous mode
 .
 Sent 1 packets.
 [ 1154.337949] v0p0id1676: left promiscuous mode
 [ 1154.360924] v0p0id1676: entered promiscuous mode
 .
 Sent 1 packets.
 [ 1154.383522] v0p0id1676: left promiscuous mode

 All test results:

 1..1
 ok 1 1676 - NETEM nested duplicate 100%

Reported-by: William Liu <will@willsroot.io>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
 .../tc-testing/tc-tests/qdiscs/netem.json     | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json
index 3c4444961488..1211497b2acc 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json
@@ -336,5 +336,30 @@
         "teardown": [
             "$TC qdisc del dev $DUMMY handle 1: root"
         ]
+    },
+    {
+        "id": "1676",
+        "name": "NETEM nested duplicate 100%",
+        "category": ["qdisc", "netem"],
+        "setup": [
+            "$TC qdisc add dev $DEV1 root handle 1: netem limit 1 duplicate 100%",
+            "$TC qdisc add dev $DEV1 parent 1: handle 2: netem gap 1 limit 1 duplicate 100% delay 1us reorder 100%"
+        ],
+        "teardown": [
+            "$TC qdisc del dev $DEV1 root"
+        ],
+        "plugins": {
+            "requires": ["nsPlugin", "scapyPlugin"]
+        },
+        "scapy": {
+            "iface": "$DEV0",
+            "count": 5,
+            "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/TCP(sport=12345, dport=80)"
+        },
+        "cmdUnderTest": "$TC -s qdisc show dev $DEV1",
+        "expExitCode": "0",
+        "verifyCmd": "$TC -s qdisc show dev $DEV1",
+        "matchPattern": "Sent [0-9]+ bytes [0-9]+ pkt",
+        "matchCount": "2"
     }
 ]
-- 
2.34.1