def test_fetch_books(self):
        """
        Must generate list of dicts with Books data depending on different criteria.
        """
        self.assertTrue(isinstance(Book.fetch_books('book'), list))

        self.assertEqual(len(Book.fetch_books('Second Book')), 1)
        self.assertEqual(len(Book.fetch_books('book')), 7)
        self.assertEqual(len(Book.fetch_books('ook')), 7)
        self.assertEqual(len(Book.fetch_books('trueAuthorNew')), 3)
        self.assertEqual(len(Book.fetch_books('author')), 7)
        self.assertEqual(len(Book.fetch_books('new')), 3)
        self.assertEqual(len(Book.fetch_books('True')), 3)