def test_get_with_invalid_election_id_non_integer_election_id(self):
        response = self.client.get(
            reverse('results-export'),
            { 'election': 'hey' },
            HTTP_REFERER=reverse('results'),
            follow=True
        )

        messages = list(response.context['messages'])
        self.assertEqual(
            messages[0].message,
            'You specified a non-integer election ID.'
        )
        self.assertRedirects(response, reverse('results'))
def test_lens_makers_formula():
    n1, n2 = symbols('n1, n2')
    m1 = Medium('m1', permittivity=e0, n=1)
    m2 = Medium('m2', permittivity=e0, n=1.33)
    assert lens_makers_formula(n1, n2, 10, -10) == 5*n2/(n1 - n2)
    assert ae(lens_makers_formula(m1, m2, 10, -10), -20.15, 2)
    assert ae(lens_makers_formula(1.33, 1, 10, -10),  15.15, 2)