Merge branch '4139-test_send_timeout-check-can-be-unstable-9.18' into 'bind-9.18'

[9.18] Make the test_send_timeout check more stable

See merge request isc-projects/bind9!8219

bin/tests/system/pytest_custom_markers.py

@@ -40,3 +40,21 @@ have_libxml2 = pytest.mark.skipif(
 have_json_c = pytest.mark.skipif(
     not feature_test("--have-json-c"), reason="json-c support disabled in the build"
 )
+
+
+try:
+    import flaky as flaky_pkg
+except ModuleNotFoundError:
+    # In case the flaky package is not installed, run the tests as usual
+    # without any attempts to re-run them.
+    # pylint: disable=unused-argument
+    def flaky(*args, **kwargs):
+        """Mock decorator that doesn't do anything special, just returns the function."""
+
+        def wrapper(wrapped_obj):
+            return wrapped_obj
+
+        return wrapper
+
+else:
+    flaky = flaky_pkg.flaky

bin/tests/system/timeouts/tests_tcp_timeouts.py

@@ -185,6 +185,7 @@ def test_long_axfr(named_port):
         assert soa is not None
 
 
+@pytest_custom_markers.flaky(max_runs=3)
 def test_send_timeout(named_port):
     with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
         sock.connect(("10.53.0.1", named_port))