Merge bitcoin/bitcoin#24269: test: add functional test for `-discover`

bff05bd7456d3634b0c83539293a753db6d76376 test: add functional test for -discover (brunoerg)

Pull request description:

  This PR adds a functional test for `-discover`. It tests different scenarios where `localaddresses` should be empty or may contain the addresses. Obs: `localaddresses` is not always accurate, so it's not possible to ensure (100%) it will contain any addresses.

  https://github.com/bitcoin/bitcoin/blob/515200298b555845696a07ae2bc0a84a5dd02ae4/src/init.cpp#L449

  Obs: See #24258  - It adds test coverage for this field but for nodes with proxy.

ACKs for top commit:
  mzumsande:
    Code review ACK bff05bd7456d3634b0c83539293a753db6d76376
  achow101:
    ACK bff05bd7456d3634b0c83539293a753db6d76376
  rajarshimaitra:
    tACK bff05bd7456d3634b0c83539293a753db6d76376

Tree-SHA512: 8782497c146bce1ba86fda6146f3847465d7069f2cb6b84f2afc8f3b43efa813442bffe7447e9ce02adee304100b60365409bf0e5d875dfb880038442feec2a6

2 files changed, 76 insertions, 0 deletions

diff --git a/test/functional/feature_discover.py b/test/functional/feature_discover.py
new file mode 100755
index 0000000000..7f4b81114e
--- /dev/null
+++ b/test/functional/feature_discover.py
@@ -0,0 +1,75 @@
+#!/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 -discover command."""
+
+import socket
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal
+
+
+def is_valid_ipv4_address(address):
+    try:
+        socket.inet_aton(address)
+    except socket.error:
+        return False
+    return True
+
+
+def is_valid_ipv6_address(address):
+    try:
+        socket.inet_pton(socket.AF_INET6, address)
+    except socket.error:
+        return False
+    return True
+
+
+class DiscoverTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.bind_to_localhost_only = False
+        self.num_nodes = 1
+
+    def validate_addresses(self, addresses_obj):
+        for address_obj in addresses_obj:
+            address = address_obj['address']
+            self.log.info(f"Validating {address}")
+            valid = (is_valid_ipv4_address(address)
+                     or is_valid_ipv6_address(address))
+            assert_equal(valid, True)
+
+    def test_local_addresses(self, test_case, *, expect_empty=False):
+        self.log.info(f"Restart node with {test_case}")
+        self.restart_node(0, test_case)
+        network_info = self.nodes[0].getnetworkinfo()
+        network_enabled = [n for n in network_info['networks']
+                           if n['reachable'] and n['name'] in ['ipv4', 'ipv6']]
+        local_addrs = list(network_info["localaddresses"])
+        if expect_empty or not network_enabled:
+            assert_equal(local_addrs, [])
+        elif len(local_addrs) > 0:
+            self.validate_addresses(local_addrs)
+
+    def run_test(self):
+        test_cases = [
+            ["-listen", "-discover"],
+            ["-discover"],
+        ]
+
+        test_cases_empty = [
+            ["-discover=0"],
+            ["-listen", "-discover=0"],
+            [],
+        ]
+
+        for test_case in test_cases:
+            self.test_local_addresses(test_case, expect_empty=False)
+
+        for test_case in test_cases_empty:
+            self.test_local_addresses(test_case, expect_empty=True)
+
+
+if __name__ == '__main__':
+    DiscoverTest().main()
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index d50d22b75c..628450f278 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -277,6 +277,7 @@ BASE_SCRIPTS = [
     'feature_dersig.py',
     'feature_cltv.py',
     'rpc_uptime.py',
+    'feature_discover.py',
     'wallet_resendwallettransactions.py --legacy-wallet',
     'wallet_resendwallettransactions.py --descriptors',
     'wallet_fallbackfee.py --legacy-wallet',