def assert_finds(self, query, books):
"""Takes a query and tests against books expected to be found."""
tree = etree.fromstring(
self.client.get('/opds/search/?%s' % query).content)
elem_ids = tree.findall('.//%s/%s' % (AtomNS('entry'), AtomNS('id')))
slugs = [WLURI(elem.text).slug for elem in elem_ids]
self.assertEqual(set(slugs), set(b.slug for b in books),
u"OPDS search '%s' failed." % query)
