def testCheckedOutTo(self):
"""
A book should always be checked out to a customer
or be back at the library(None)
"""
lib = Library()
lib.add_books(self._book)
self.assertIsNone(lib.books_all[0].checked_out_to)
# when a book is checked out it should obtain status checked_out_to
# to point to a cus
cus = "Garry"
lib.checkout(self._book,cus)
self.assertEqual(cus,self._book.checked_out_to)
