Tests pass now

netbox/dcim/api/serializers.py

@@ -334,7 +334,7 @@ class InterfaceSerializer(serializers.ModelSerializer):
 
     class Meta:
         model = Interface
-        fields = ['id', 'device', 'name', 'form_factor', 'mgmt_only', 'description', 'is_connected']
+        fields = ['id', 'device', 'name', 'form_factor', 'mac_address', 'mgmt_only', 'description', 'is_connected']
 
 
 class InterfaceNestedSerializer(InterfaceSerializer):
@@ -348,7 +348,7 @@ class InterfaceDetailSerializer(InterfaceSerializer):
     connected_interface = InterfaceSerializer(source='get_connected_interface')
 
     class Meta(InterfaceSerializer.Meta):
-        fields = ['id', 'device', 'name', 'form_factor', 'mgmt_only', 'description', 'is_connected',
+        fields = ['id', 'device', 'name', 'form_factor', 'mac_address', 'mgmt_only', 'description', 'is_connected',
                   'connected_interface']
 
 

netbox/dcim/views.py

@@ -1252,6 +1252,7 @@ def interface_add(request, pk):
                     'device': device.pk,
                     'name': name,
                     'form_factor': form.cleaned_data['form_factor'],
+                    'mac_address': form.cleaned_data['mac_address'],
                     'mgmt_only': form.cleaned_data['mgmt_only'],
                     'description': form.cleaned_data['description'],
                 })