I want to test the update function of a view set

from rest_framework.viewsets import ModelViewSet
@extend_schema(tags=['Customers'])
class CustomerViewSet(ModelViewSet):
    """ This view can be used to see all the customers"""
    serializer_class = CustomerSerializer
    .....
    def update(self, request, *args, **kwargs):
        return self._update_customer(request, *args, **kwargs)

The route is mapped here (like the other view sets):

router.register(r'customers', CustomerViewSet, basename='customer')

Like for my other view sets where it works,
i test the update method by resolving it in my test case

from django.test import TestCase
from rest_framework.reverse import reverse
......
class CustomerUpdateViewTest(TestCase):
         .....
         def test_customer_missing(self):
             url = reverse('customer-detail', [2])        
             token = create_access_token(self.my_user)

             data = {
               'customer': 'new name customer'
             }

             response = self.client.patch(url, data, 
                content_type="application/json",
                HTTP_AUTHORIZATION=f'Bearer {token}')

I have created before in a setup method many customers
But the self.client.patch instruction give always a 404 error

In my running application,
the path is /api/customers/x (like in my test where x = a customer identifier)
and is an HTTP PATCH verb

For my similar views, i test in a very similar way and it works.

Do you have already encountered such a problem ?
If yes, what can i do to solve this problem ?

Thank you very much in advance,
Thomas