From fbee0ba2ab3c0aa8ee3c18ceed64fba24cc3144f Mon Sep 17 00:00:00 2001
From: Mystical <125946525+mystical-prog@users.noreply.github.com>
Date: Mon, 23 Jun 2025 01:00:46 +0530
Subject: [PATCH] added newsfragment

---
 newsfragments/690.feature.rst                 |  1 +
 .../pubsub/test_gossipsub_px_and_backoff.py   | 50 +++++++++++++++++++
 2 files changed, 51 insertions(+)
 create mode 100644 newsfragments/690.feature.rst

diff --git a/newsfragments/690.feature.rst b/newsfragments/690.feature.rst
new file mode 100644
index 00000000..450ffdfd
--- /dev/null
+++ b/newsfragments/690.feature.rst
@@ -0,0 +1 @@
+added peer exchange and backoff logic as part of Gossipsub v1.1 upgrade
diff --git a/tests/core/pubsub/test_gossipsub_px_and_backoff.py b/tests/core/pubsub/test_gossipsub_px_and_backoff.py
index a47aa3ce..8c623ebd 100644
--- a/tests/core/pubsub/test_gossipsub_px_and_backoff.py
+++ b/tests/core/pubsub/test_gossipsub_px_and_backoff.py
@@ -113,3 +113,53 @@ async def test_unsubscribe_backoff():
         assert host_0.get_id() in gsub1.mesh[topic], (
             "peer should be able to rejoin after backoff"
         )
+
+
+@pytest.mark.trio
+async def test_peer_exchange():
+    async with PubsubFactory.create_batch_with_gossipsub(
+        3,
+        heartbeat_interval=0.5,
+        do_px=True,
+        px_peers_count=1,
+    ) as pubsubs:
+        gsub0 = pubsubs[0].router
+        gsub1 = pubsubs[1].router
+        gsub2 = pubsubs[2].router
+        assert isinstance(gsub0, GossipSub)
+        assert isinstance(gsub1, GossipSub)
+        assert isinstance(gsub2, GossipSub)
+        host_0 = pubsubs[0].host
+        host_1 = pubsubs[1].host
+        host_2 = pubsubs[2].host
+
+        topic = "test_peer_exchange"
+
+        # connect hosts
+        await connect(host_1, host_0)
+        await connect(host_1, host_2)
+        await trio.sleep(0.5)
+
+        # all join the topic and 0 <-> 1 and 1 <-> 2 graft
+        await pubsubs[1].subscribe(topic)
+        await pubsubs[0].subscribe(topic)
+        await pubsubs[2].subscribe(topic)
+        await gsub1.emit_graft(topic, host_0.get_id())
+        await gsub1.emit_graft(topic, host_2.get_id())
+        await gsub0.emit_graft(topic, host_1.get_id())
+        await gsub2.emit_graft(topic, host_1.get_id())
+        await trio.sleep(1)
+
+        # ensure peer is registered in mesh
+        assert host_0.get_id() in gsub1.mesh[topic]
+        assert host_2.get_id() in gsub1.mesh[topic]
+        assert host_2.get_id() not in gsub0.mesh[topic]
+
+        # host_1 unsubscribes from the topic
+        await gsub1.leave(topic)
+        await trio.sleep(1)  # Wait for heartbeat to update mesh
+        assert topic not in gsub1.mesh
+
+        # Wait for gsub0 to graft host_2 into its mesh via PX
+        await trio.sleep(1)
+        assert host_2.get_id() in gsub0.mesh[topic]