Call external function without sending 'self' arg

Question

I'm writing tests for a Django application and using a attribute on my test class to store which view it's supposed to be testing, like this:

# IN TESTS.PY
class OrderTests(TestCase, ShopTest):
    _VIEW = views.order

    def test_gateway_answer(self):
        url = 'whatever url'
        request = self.request_factory(url, 'GET')
        self._VIEW(request, **{'sku': order.sku})


# IN VIEWS.PY
def order(request, sku)
    ...

My guess is that the problem I'm having is caused because since I'm calling an attribute of the OrderTests class, python assumes I wanna send self and then order get the wrong arguments. Easy to solve... just not use it as a class attribute, but I was wondering if there's a way to tell python to not send self in this case.

Thanks.

Answer 1

This happens because in Python functions are descriptors, so when they are accessed on class instances they bind their first (assumed self) parameter to the instance.

You could access _VIEW on the class, not on the instance:

class OrderTests(TestCase, ShopTest):
    _VIEW = views.order

    def test_gateway_answer(self):
        url = 'whatever url'
        request = self.request_factory(url, 'GET')
        OrderTests._VIEW(request, **{'sku': order.sku})

Alternatively, you can wrap it in staticmethod to prevent it being bound to the instance:

class OrderTests(TestCase, ShopTest):
    _VIEW = staticmethod(views.order)

    def test_gateway_answer(self):
        url = 'whatever url'
        request = self.request_factory(url, 'GET')
        self._VIEW(request, **{'sku': order.sku})