fix: Auto-enable adj-rib-out when route-refresh capability is enabled

Route-refresh requires cached routes to resend. When adj-rib-out is
disabled (default), cached_routes() returns empty and no UPDATE is
sent after receiving ROUTE-REFRESH.

Now ParseNeighbor._post_capa_rr() auto-enables adj-rib-out when
route-refresh is configured, with a warning log.

Fixes #1151

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: thomas-mangin

src/exabgp/configuration/neighbor/__init__.py

@@ -500,8 +500,15 @@ def _post_capa_nexthop(self, neighbor: Neighbor, local: dict[str, Any]) -> None:
 
     def _post_capa_rr(self, neighbor: Neighbor) -> None:
         if neighbor.capability.route_refresh:
-            if neighbor.adj_rib_out:
-                log.debug(lazymsg('neighbor.capability.route_refresh action=enable_adj_rib_out'), 'configuration')
+            if not neighbor.adj_rib_out:
+                log.warning(
+                    lazymsg(
+                        'neighbor.route_refresh.adj_rib_out peer={peer} action=auto_enabled reason=route_refresh_requires_cache',
+                        peer=neighbor.session.peer_address,
+                    ),
+                    'configuration',
+                )
+                neighbor.adj_rib_out = True
 
     def _post_routes(self, neighbor: Neighbor, local: dict[str, Any]) -> None:
         # NOTE: this may modify change but does not matter as want to modified
@@ -548,6 +555,7 @@ def post(self) -> bool:
         self._post_capa_default(neighbor, local)
         self._post_capa_addpath(neighbor, local, families)
         self._post_capa_nexthop(neighbor, local)
+        self._post_capa_rr(neighbor)
         self._post_routes(neighbor, local)
 
         neighbor.api = ParseAPI.flatten(local.pop('api', {}))

tests/unit/configuration/test_route_refresh_adj_rib_out.py

@@ -0,0 +1,73 @@
+"""Test route-refresh capability auto-enables adj-rib-out.
+
+When route-refresh is enabled, adj-rib-out must be enabled for it to function.
+ParseNeighbor._post_capa_rr auto-enables adj-rib-out when route-refresh is configured.
+
+See: https://github.com/Exa-Networks/exabgp/issues/1151
+"""
+
+from exabgp.bgp.neighbor.neighbor import Neighbor
+from exabgp.protocol.ip import IP
+
+
+class TestRouteRefreshAdjRibOut:
+    """Test that route-refresh capability auto-enables adj-rib-out."""
+
+    def _create_neighbor(self) -> Neighbor:
+        """Create a minimal Neighbor for testing."""
+        neighbor = Neighbor()
+        neighbor.session.peer_address = IP.from_string('192.168.1.1')
+        return neighbor
+
+    def test_adj_rib_out_auto_enabled_when_route_refresh_enabled(self) -> None:
+        """When route-refresh is enabled and adj-rib-out is False, auto-enable it."""
+        from exabgp.configuration.neighbor import ParseNeighbor
+
+        neighbor = self._create_neighbor()
+        neighbor.capability.route_refresh = 2  # REFRESH.NORMAL
+        neighbor.adj_rib_out = False
+
+        # Simulate what ParseNeighbor.post() does
+        parser = ParseNeighbor.__new__(ParseNeighbor)
+        parser._post_capa_rr(neighbor)
+
+        assert neighbor.adj_rib_out is True
+
+    def test_adj_rib_out_unchanged_when_already_enabled(self) -> None:
+        """When adj-rib-out is already True, it stays True."""
+        from exabgp.configuration.neighbor import ParseNeighbor
+
+        neighbor = self._create_neighbor()
+        neighbor.capability.route_refresh = 2  # REFRESH.NORMAL
+        neighbor.adj_rib_out = True
+
+        parser = ParseNeighbor.__new__(ParseNeighbor)
+        parser._post_capa_rr(neighbor)
+
+        assert neighbor.adj_rib_out is True
+
+    def test_adj_rib_out_unchanged_when_route_refresh_disabled(self) -> None:
+        """When route-refresh is disabled, adj-rib-out is not changed."""
+        from exabgp.configuration.neighbor import ParseNeighbor
+
+        neighbor = self._create_neighbor()
+        neighbor.capability.route_refresh = 0  # Disabled
+        neighbor.adj_rib_out = False
+
+        parser = ParseNeighbor.__new__(ParseNeighbor)
+        parser._post_capa_rr(neighbor)
+
+        assert neighbor.adj_rib_out is False
+
+    def test_enhanced_route_refresh_also_enables_adj_rib_out(self) -> None:
+        """Enhanced route-refresh (value 4) also auto-enables adj-rib-out."""
+        from exabgp.configuration.neighbor import ParseNeighbor
+
+        neighbor = self._create_neighbor()
+        neighbor.capability.route_refresh = 4  # REFRESH.ENHANCED
+        neighbor.adj_rib_out = False
+
+        parser = ParseNeighbor.__new__(ParseNeighbor)
+        parser._post_capa_rr(neighbor)
+
+        assert neighbor.adj_rib_out is True