POST checkbox value in Django Unit Test

I'm trying to test a POST request in Django Unit Test and this POST request will be redirected to other url, but response isn't redirected and when I print the response I found there is an error message that checkbox is required, and it's the reason my request don't redirected.

Error:

AssertionError: Response didn't redirect as expected: Response code was 200 (expected 302)

HTML

    <p>
    <label for="id_is_urgent">Is urgent:</label> 
    <input checked="checked" id="id_is_urgent" name="is_urgent" type="checkbox" />
</p>
    <ul class="errorlist">
       <li>This field is required.</li>
    </ul>

test_views.py

 def test_post_order_details_view(self):
        expected_url_for_order_list = reverse('order_update', args=(self.order.id,))
        response = self.client.post(reverse('order_update', args=(self.order.id,)),
                                {'customer': str(self.customer.id),
                                 'service': str(self.service.id),
                                 'order_type': str(self.order_type.id),
                                 'assigned_to': str(self.user.id),
                                 'status': str(self.order_status.id),
                                 'order_status_action': str(self.order_status_action.id),
                                 'is_urgent': True}, follow=True
        self.assertEqual(response.status_code, 200)

view.py

def order_update(request, pk, template_name='orders_app/order_details.html'):
    order = get_object_or_404(CustomerOrder, pk=pk)
    order_lines = OrderLine.objects.filter(order_id=pk)
    customer = order.customer
    service = order.service
    contacts = order.customer.customer_contacts_info.all()

    form = OrderForm(request.POST or None, instance=order)

    if request.method == 'POST':
        if form.is_valid():
            order = form.save()
            messages.info(request, 'Customer Order %s save successfully' % order.id)
            return redirect(reverse('order_update', args=(order.id,)))
    return render(request, template_name, {'form': form,
                                           'order': order,
                                           'lines': order_lines,
                                           'customer': customer,
                                           'service': service,
                                           'contacts': contacts})