django test a templatetag which uses the request

Question

I'm using a custom templatetag to calculate currency values, currency is chosen from a select element. when the user choose the currency he want work with I save the chosen currency in the session and refresh the page.

a templatetag shows the value calculated for the choosen currency.

in any template

{% load currency %}
{% set_currency request 156 %}

in my_app/templatetags/currency.py

from django.conf import settings
from djmoney_rates.utils import convert_money
register = template.Library()

@register.inclusion_tag('includes/price.html')
def set_currency(request, price):
    # currency_session could be 'USD', 'EUR' ...
    currency_session = request.session.get(settings.CURRENCY_SESSION_KEY, settings.DEFAULT_CURRENCY)
    money = convert_money(price, settings.DEFAULT_CURRENCY, currency_session)
    return {'amount': '%d' % money.amount, 'currency': money.currency}

includes/price.html is just

<span class="amount">{{amount}}</span>
<span class="currency">{{currency}}</span>

Now I'm wondering the way to test this templatetag, how to pass the request, and how make session to exists in that request.

Answer 1

I would only test the function.

from django.test import TestCase, RequestFactory
from django.conf import settings
from my_app.templatetags.currency import set_currency

class SetCurrencyTestCase(TestCase):

    def setUp(self):
        self.factory = RequestFactory()

    def test_set_currency(self):
        request = self.factory.get('/any/path/really/')
        request.session = {
            settings.CURRENCY_SESSION_KEY: settings.DEFAULT_CURRENCY
        }

        response = set_currency(request, 156)

        self.assertEqual(response['amount'], 42)
        self.assertEqual(response['currency'], 'BTC')

I'd also consider setting request.session without using settings, but that depends on your application.