Add test for switch reachability notif on fabric devices

Summary:
Add a test that will ensure that fabric switches are getting notified of
the switch reachability information.

Reviewed By: jasmeetbagga

Differential Revision: D61036834

fbshipit-source-id: 003375b048aac0b2897b66f9d7c39eb1a188b0ba

fboss/agent/test/agent_hw_tests/AgentFabricSwitchTests.cpp

@@ -402,4 +402,40 @@ TEST_F(AgentFabricSwitchTest, dtlQueueWatermarks) {
 
   verifyAcrossWarmBoots([]() {}, verify);
 }
+
+TEST_F(AgentFabricSwitchTest, switchReachability) {
+  auto verify = [this]() {
+    utility::checkFabricPortsActiveState(
+        getAgentEnsemble(),
+        masterLogicalFabricPortIds(),
+        true /*expectActive*/);
+    for (auto switchId : getFabricSwitchIdsWithPorts()) {
+      bool switchReachabilityWorking = false;
+      WITH_RETRIES({
+        auto switchIter = getSw()->getSwitchReachability().find(switchId);
+        EXPECT_EVENTUALLY_TRUE(
+            switchIter != getSw()->getSwitchReachability().end());
+        for (auto& [destinationSwitchId, portGroupId] :
+             *switchIter->second.switchIdToFabricPortGroupMap()) {
+          auto portGroupIter =
+              switchIter->second.fabricPortGroupMap()->find(portGroupId);
+          if (portGroupIter != switchIter->second.fabricPortGroupMap()->end()) {
+            XLOG(DBG0) << "On local switch id " << switchId
+                       << ", destination switch id " << destinationSwitchId
+                       << " reachability available over port group ID "
+                       << portGroupId << ", with group size "
+                       << portGroupIter->second.size();
+            // Fabric device does not have physical rechability to
+            // any other device, so no ports expected in port group.
+            EXPECT_EQ(portGroupIter->second.size(), 0);
+            switchReachabilityWorking = true;
+          }
+        }
+        EXPECT_EVENTUALLY_TRUE(switchReachabilityWorking);
+      });
+    }
+  };
+
+  verifyAcrossWarmBoots([]() {}, verify);
+}
 } // namespace facebook::fboss