Fix(eos_designs): Better error message when missing 'evpn_multicast' for PIM l3 interfaces

ansible_collections/arista/avd/molecule/eos_designs_negative_unit_tests/inventory/host_vars/failure-missing-evpn-multicast-l3-with-pim.yml

@@ -43,4 +43,4 @@ tenants:
 
 expected_error_message: >-
   'pim: enabled' set on l3_interface 'Ethernet1' on 'failure-missing-evpn-multicast-l3-with-pim'
-  requires evpn_l3_multicast: enabled: true under VRF 'Tenant_A_OP_Zone_MC' or Tenant 'FABRIC'
+  requires 'evpn_l3_multicast.enabled: true' under VRF 'Tenant_A_OP_Zone_MC' or Tenant 'FABRIC'

ansible_collections/arista/avd/molecule/eos_designs_negative_unit_tests/inventory/host_vars/failure-missing-evpn-multicast-with-pim.yml

@@ -0,0 +1,48 @@
+type: l3leaf
+underlay_multicast: true
+# When this is set to false, the VRF won't have evpn_l3_multicast enabled
+# and PIM will fail
+evpn_multicast: false
+
+l3leaf:
+  defaults:
+    # LOOPBACK AND VTEP MANAGEMENT
+    loopback_ipv4_pool: 10.10.0.0/24
+    vtep_loopback_ipv4_pool: 10.11.0.0/24
+    vtep_loopback: Loopback1
+  nodes:
+    - name: failure-missing-evpn-multicast-with-pim
+      id: 3
+      bgp_as: 65101
+      filter:
+        tags: ['evpn-multicast-pegs']
+
+tenants:
+  - name: FABRIC
+    mac_vrf_vni_base: 10000
+    evpn_l3_multicast:
+      enabled: true
+      evpn_underlay_l3_multicast_group_ipv4_pool: 232.0.0.0/20
+    vrfs:
+      - name: Tenant_A_OP_Zone_MC
+        description: "Tenant_A_OP_Zone"
+        vrf_vni: 10
+        vtep_diagnostic:
+          loopback: 31
+          loopback_ip_range: 10.255.1.0/24
+        svis:
+          - id: 210
+            name: Tenant_A_OP_Zone_1
+            tags: ['evpn-multicast-l3']
+        l3_interfaces:
+          - nodes: [ failure-missing-evpn-multicast-with-pim ]
+            interfaces: [ Ethernet1 ]
+            ip_addresses: [ 10.254.248.0/31 ]
+            descriptions: [ "L3 Link to RPs" ]
+            enabled: true
+            pim:
+              enabled: true
+
+expected_error_message: >-
+  'pim: enabled' set on l3_interface 'Ethernet1' on 'failure-missing-evpn-multicast-with-pim'
+  requires 'evpn_multicast: true' at the fabric level

ansible_collections/arista/avd/molecule/eos_designs_negative_unit_tests/inventory/hosts.yml

@@ -93,6 +93,7 @@ all:
             failure-missing-evpn-vlan-bundle_svi:
             failure-missing-evpn-multicast-l3-with-pim:
             failure-missing-evpn-multicast-peg-rps:
+            failure-missing-evpn-multicast-with-pim:
             failure-duplicate-evpn-vlan-bundle-name:
             failure-no-local-path-group-in-default-policy:
             ipv4-acl-in-missing-on-wan-interface:

python-avd/pyavd/_eos_designs/structured_config/network_services/ethernet_interfaces.py

@@ -134,10 +134,17 @@ def ethernet_interfaces(self: AvdStructuredConfigNetworkServices) -> list | None
 
                             if get(l3_interface, "pim.enabled"):
                                 if not vrf.get("_evpn_l3_multicast_enabled"):
-                                    msg = (
-                                        f"'pim: enabled' set on l3_interface '{interface_name}' on '{self.shared_utils.hostname}' requires evpn_l3_multicast:"
-                                        f" enabled: true under VRF '{vrf['name']}' or Tenant '{tenant['name']}'"
-                                    )
+                                    # Possibly the key was not set because `evpn_multicast` is not set to `true`.
+                                    if not self.shared_utils.evpn_multicast:
+                                        msg = (
+                                            f"'pim: enabled' set on l3_interface '{interface_name}' on '{self.shared_utils.hostname}' requires "
+                                            "'evpn_multicast: true' at the fabric level"
+                                        )
+                                    else:
+                                        msg = (
+                                            f"'pim: enabled' set on l3_interface '{interface_name}' on '{self.shared_utils.hostname}' requires "
+                                            f"'evpn_l3_multicast.enabled: true' under VRF '{vrf['name']}' or Tenant '{tenant['name']}'"
+                                        )
                                     raise AristaAvdError(
                                         msg,
                                     )