From 986944b5252ad23ed33c2b30450cdbbb8e19b51c Mon Sep 17 00:00:00 2001
From: vitthalmagadum <vitthal.magadum-ext@arista.com>
Date: Fri, 21 Feb 2025 02:39:24 -0500
Subject: [PATCH] Added negative testing in VerifyReachability

---
 anta/input_models/connectivity.py           | 10 +++---
 anta/tests/connectivity.py                  |  8 ++++-
 examples/tests.yaml                         |  1 +
 tests/units/anta_tests/test_connectivity.py | 38 +++++++++++++++++++++
 4 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/anta/input_models/connectivity.py b/anta/input_models/connectivity.py
index f967e775b..4c526c04c 100644
--- a/anta/input_models/connectivity.py
+++ b/anta/input_models/connectivity.py
@@ -23,13 +23,15 @@ class Host(BaseModel):
     source: IPv4Address | IPv6Address | Interface
     """Source address IP or egress interface to use."""
     vrf: str = "default"
-    """VRF context. Defaults to `default`."""
+    """VRF context."""
     repeat: int = 2
-    """Number of ping repetition. Defaults to 2."""
+    """Number of ping repetition."""
     size: int = 100
-    """Specify datagram size. Defaults to 100."""
+    """Specify datagram size."""
     df_bit: bool = False
-    """Enable do not fragment bit in IP header. Defaults to False."""
+    """Enable do not fragment bit in IP header."""
+    expected_unreachable: bool = False
+    """Indicates whether the expected network should be unreachable."""
 
     def __str__(self) -> str:
         """Return a human-readable string representation of the Host for reporting.
diff --git a/anta/tests/connectivity.py b/anta/tests/connectivity.py
index 2fd58c1bb..84d6bc965 100644
--- a/anta/tests/connectivity.py
+++ b/anta/tests/connectivity.py
@@ -47,6 +47,7 @@ class VerifyReachability(AntaTest):
               vrf: default
               df_bit: True
               size: 100
+              expected_unreachable: true
     ```
     """
 
@@ -89,9 +90,14 @@ def test(self) -> None:
         self.result.is_success()
 
         for command, host in zip(self.instance_commands, self.inputs.hosts):
-            if f"{host.repeat} received" not in command.json_output["messages"][0]:
+            # Verifies the network is reachable
+            if not host.expected_unreachable and f"{host.repeat} received" not in command.json_output["messages"][0]:
                 self.result.is_failure(f"{host} - Unreachable")
 
+            # Verifies the network is unreachable.
+            if host.expected_unreachable and "0 received" not in command.json_output["messages"][0]:
+                self.result.is_failure(f"{host} - Network is expected to be unreachable but found reachable.")
+
 
 class VerifyLLDPNeighbors(AntaTest):
     """Verifies the connection status of the specified LLDP (Link Layer Discovery Protocol) neighbors.
diff --git a/examples/tests.yaml b/examples/tests.yaml
index f5fd3ebd0..65e5de64b 100644
--- a/examples/tests.yaml
+++ b/examples/tests.yaml
@@ -140,6 +140,7 @@ anta.tests.connectivity:
           vrf: default
           df_bit: True
           size: 100
+          expected_unreachable: true
 anta.tests.cvx:
   - VerifyActiveCVXConnections:
       # Verifies the number of active CVX Connections.
diff --git a/tests/units/anta_tests/test_connectivity.py b/tests/units/anta_tests/test_connectivity.py
index 86ada5dea..96d39dde5 100644
--- a/tests/units/anta_tests/test_connectivity.py
+++ b/tests/units/anta_tests/test_connectivity.py
@@ -45,6 +45,23 @@
         ],
         "expected": {"result": "success"},
     },
+    {
+        "name": "success-expected-unreachable",
+        "test": VerifyReachability,
+        "eos_data": [
+            {
+                "messages": [
+                    """PING 10.0.0.1 (10.0.0.1) from 10.0.0.5 : 72(100) bytes of data.
+
+                --- 10.0.0.1 ping statistics ---
+                2 packets transmitted, 0 received, 100% packet loss, time 10ms
+                """,
+                ],
+            },
+        ],
+        "inputs": {"hosts": [{"destination": "10.0.0.1", "source": "10.0.0.5", "expected_unreachable": True}]},
+        "expected": {"result": "success"},
+    },
     {
         "name": "success-ipv6",
         "test": VerifyReachability,
@@ -268,6 +285,27 @@
         ],
         "expected": {"result": "failure", "messages": ["Host: 10.0.0.1 Source: Management0 VRF: default - Unreachable"]},
     },
+    {
+        "name": "failure-expected-unreachable",
+        "test": VerifyReachability,
+        "eos_data": [
+            {
+                "messages": [
+                    """PING 10.0.0.1 (10.0.0.1) from 10.0.0.5 : 72(100) bytes of data.
+                80 bytes from 10.0.0.1: icmp_seq=1 ttl=64 time=0.247 ms
+                80 bytes from 10.0.0.1: icmp_seq=2 ttl=64 time=0.072 ms
+
+                --- 10.0.0.1 ping statistics ---
+                2 packets transmitted, 2 received, 0% packet loss, time 0ms
+                rtt min/avg/max/mdev = 0.072/0.159/0.247/0.088 ms, ipg/ewma 0.370/0.225 ms
+
+                """,
+                ],
+            },
+        ],
+        "inputs": {"hosts": [{"destination": "10.0.0.1", "source": "10.0.0.5", "expected_unreachable": True}]},
+        "expected": {"result": "failure", "messages": ["Host: 10.0.0.1 Source: 10.0.0.5 VRF: default - Network is expected to be unreachable but found reachable."]},
+    },
     {
         "name": "success",
         "test": VerifyLLDPNeighbors,