How to use the freezer.storage.storage.Backup function in freezer

def test__find_previous_backup_with_max_level(self):
        backup = storage.Backup("name", 1234)
        i1 = storage.Backup("name", 1234, 1, backup)
        i2 = storage.Backup("name", 1234, 2, backup)
        backup.add_increment(i1)
        backup.add_increment(i2)
        b = storage.Storage._find_previous_backup([backup], False, 2, False, 0)
        assert not b

def test_remove_older_than(self):
        t = storage.Storage()
        t.get_backups = mock.Mock()
        r1 = storage.Backup("host_backup", 1000)
        r2 = storage.Backup("host_backup", 2000)
        t.get_backups.return_value = [
            r1,
            r2,
            storage.Backup("host_backup", 3000),
            storage.Backup("host_backup", 4000),
            storage.Backup("host_backup_f", 1000),
            storage.Backup("host_backup", 5000),
        ]
        t.remove_backup = mock.Mock()
        t.remove_older_than(3000, "host_backup")
        t.remove_backup.assert_any_call(r1)
        t.remove_backup.assert_any_call(r2)
        assert t.remove_backup.call_count == 2

def test_restore_latest_backup(self):
        t = storage.Storage()
        t.get_backups = mock.Mock()
        last = storage.Backup("host_backup", 5000)
        t.get_backups.return_value = [
            storage.Backup("host_backup", 1000),
            storage.Backup("host_backup", 2000),
            storage.Backup("host_backup", 3000),
            storage.Backup("host_backup", 4000),
            storage.Backup("host_backup_f", 1000),
            last
        ]
        self.assertRaises(IndexError, t.find_one, "")
        assert t.find_one("host_backup") == last

def test_restore_from_date(self):
        t = storage.Storage()
        t.get_backups = mock.Mock()
        backup_restore = storage.Backup("host_backup", 3000)
        t.get_backups.return_value = [
            storage.Backup("host_backup", 1000),
            storage.Backup("host_backup", 2000),
            backup_restore,
            storage.Backup("host_backup", 4000),
            storage.Backup("host_backup_f", 1000),
            storage.Backup("host_backup", 5000),
        ]
        assert t.find_one("host_backup", 3234) == backup_restore

def test_add_increment_raises(self):
        backup = storage.Backup("name", 1234, level=3)
        self.assertRaises(ValueError, backup.add_increment, None)

def test__find_previous_backup(self):
        backup = storage.Backup("name", 1234)
        b = storage.Storage._find_previous_backup([backup], False, 2, False, 0)
        assert b == backup

def test_remove_older_than(self):
        t = storage.Storage()
        t.get_backups = mock.Mock()
        r1 = storage.Backup("host_backup", 1000)
        r2 = storage.Backup("host_backup", 2000)
        t.get_backups.return_value = [
            r1,
            r2,
            storage.Backup("host_backup", 3000),
            storage.Backup("host_backup", 4000),
            storage.Backup("host_backup_f", 1000),
            storage.Backup("host_backup", 5000),
        ]
        t.remove_backup = mock.Mock()
        t.remove_older_than(3000, "host_backup")
        t.remove_backup.assert_any_call(r1)
        t.remove_backup.assert_any_call(r2)
        assert t.remove_backup.call_count == 2

def test_backup_increment(self):
        backup = storage.Backup("name", 1234)
        self.assertRaises(ValueError, backup.add_increment, backup)
        increment = storage.Backup("name", 4567, 1, backup)
        backup.add_increment(increment)
        self.assertEqual(len(backup.increments), 2)

def test_find_latest_backup_respects_increments_timestamp(self):
        test_backup = storage.Backup("host_backup", 5500)
        increment = storage.Backup("host_backup", 6000, 1, test_backup)
        test_backup.add_increment(increment)
        t = storage.Storage()
        t.get_backups = mock.Mock()
        t.get_backups.return_value = [
            test_backup,
            storage.Backup("host_backup", 2000),
            storage.Backup("host_backup", 3000),
            storage.Backup("host_backup", 4000),
            storage.Backup("host_backup_f", 1000),
            storage.Backup("host_backup", 5000),
        ]
        assert t.find_one("host_backup") == increment

def test_restore_from_date_increment(self):
        t = storage.Storage()
        t.get_backups = mock.Mock()
        test_backup = storage.Backup("host_backup", 1000)
        increment = storage.Backup("host_backup", 3200, 1, test_backup)
        test_backup.add_increment(increment)
        t.get_backups.return_value = [
            test_backup,
            storage.Backup("host_backup", 4000),
            storage.Backup("host_backup_f", 1000),
            storage.Backup("host_backup", 5000),
        ]
        assert t.find_one("host_backup", 3234) == increment