From 48262a00f58489d705314ee3c31136133040bb0e Mon Sep 17 00:00:00 2001
From: Suhas Daftuar <sdaftuar@gmail.com>
Date: Wed, 26 Jan 2022 15:59:09 -0500
Subject: [PATCH] Add functional test for block sync from inbound peers

---
 test/functional/p2p_block_sync.py | 37 +++++++++++++++++++++++++++++++
 test/functional/test_runner.py    |  1 +
 2 files changed, 38 insertions(+)
 create mode 100755 test/functional/p2p_block_sync.py

diff --git a/test/functional/p2p_block_sync.py b/test/functional/p2p_block_sync.py
new file mode 100755
index 00000000000..d821edc1b18
--- /dev/null
+++ b/test/functional/p2p_block_sync.py
@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+# Copyright (c) 2022 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test block download
+
+Ensure that even in IBD, we'll eventually sync chain from inbound peers
+(whether we have only inbound peers or both inbound and outbound peers).
+"""
+
+from test_framework.test_framework import BitcoinTestFramework
+
+class BlockSyncTest(BitcoinTestFramework):
+
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 3
+
+    def setup_network(self):
+        self.setup_nodes()
+        # Construct a network:
+        # node0 -> node1 -> node2
+        # So node1 has both an inbound and outbound peer.
+        # In our test, we will mine a block on node0, and ensure that it makes
+        # to to both node1 and node2.
+        self.connect_nodes(0, 1)
+        self.connect_nodes(1, 2)
+
+    def run_test(self):
+        self.log.info("Setup network: node0->node1->node2")
+        self.log.info("Mining one block on node0 and verify all nodes sync")
+        self.generate(self.nodes[0], 1)
+        self.log.info("Success!")
+
+
+if __name__ == '__main__':
+    BlockSyncTest().main()
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 8416a5881d1..7b67027d6fe 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -157,6 +157,7 @@ BASE_SCRIPTS = [
     'wallet_avoidreuse.py --descriptors',
     'mempool_reorg.py',
     'mempool_persist.py',
+    'p2p_block_sync.py',
     'wallet_multiwallet.py --legacy-wallet',
     'wallet_multiwallet.py --descriptors',
     'wallet_multiwallet.py --usecli',