Add output format explicitly for html test

        self.assertEqual(result.status_code, 400)

    def test_search_html(self):

        result = self.app.post('/search', data={'q': 'test'})

        result = self.app.post('/search', data={'q': 'test', 'format': 'html'})

        self.assertIn(

            b'<span class="url_o1"><span class="url_i1">http://second.test.xyz</span></span>',

            result.data,