[test] Check user agent string from test framework connections

Add a check that new connections from the test framework to the
node have the correct user agent string. This makes bugs easier
to detect if the user agent string ever changes.

1 files changed, 6 insertions, 0 deletions

diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 24f48d5535..5bc1409ba2 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -26,6 +26,7 @@ from .descriptors import descsum_create
 from .p2p import P2P_SUBVERSION
 from .util import (
     MAX_NODES,
+    assert_equal,
     append_config,
     delete_cookie_file,
     get_auth_cookie,
@@ -545,6 +546,11 @@ class TestNode():
             # in comparison to the upside of making tests less fragile and unexpected intermittent errors less likely.
             p2p_conn.sync_with_ping()
 
+            # Consistency check that the Bitcoin Core has received our user agent string. This checks the
+            # node's newest peer. It could be racy if another Bitcoin Core node has connected since we opened
+            # our connection, but we don't expect that to happen.
+            assert_equal(self.getpeerinfo()[-1]['subver'], P2P_SUBVERSION)
+
         return p2p_conn
 
     def add_outbound_p2p_connection(self, p2p_conn, *, p2p_idx, connection_type="outbound-full-relay", **kwargs):