A.8　第19章：处理OSCON日程表的脚本和测试

示例 A-12 是 schedule1.py 模块（示例 19-9）的测试脚本，使用 py.test 库和测试运行程序实现。

示例 A-12　test_schedule1.py

import shelve
import pytest

import schedule1 as schedule


@pytest.yield_fixture
def db():
    with shelve.open(schedule.DB_NAME) as the_db:
        if schedule.CONFERENCE not in the_db:
            schedule.load_db(the_db)
        yield the_db


def test_record_class():
    rec = schedule.Record(spam=99, eggs=12)
    assert rec.spam == 99
    assert rec.eggs == 12


def test_conference_record(db):
    assert schedule.CONFERENCE in db


def test_speaker_record(db):
    speaker = db['speaker.3471']
    assert speaker.name == 'Anna Martelli Ravenscroft'


def test_event_record(db):
    event = db['event.33950']
    assert event.name == 'There *Will* Be Bugs'


def test_event_venue(db):
    event = db['event.33950']
    assert event.venue_serial == 1449

19.1.5 节分四部分列出了 schedule2.py 脚本里的代码，示例 A-13 是完整的代码清单。

示例 A-13　schedule2.py

"""
schedule2.py: 遍历OSCON的日程数据

    >>> import shelve
    >>> db = shelve.open(DB_NAME)
    >>> if CONFERENCE not in db: load_db(db)

# BEGIN SCHEDULE2_DEMO

    >>> DbRecord.set_db(db)
    >>> event = DbRecord.fetch('event.33950')
    >>> event
    <Event 'There *Will* Be Bugs'>
    >>> event.venue
    <DbRecord serial='venue.1449'>
    >>> event.venue.name
    'Portland 251'
    >>> for spkr in event.speakers:
    ...     print('{0.serial}: {0.name}'.format(spkr))
    ...
    speaker.3471: Anna Martelli Ravenscroft
    speaker.5199: Alex Martelli

# END SCHEDULE2_DEMO

    >>> db.close()

"""

# BEGIN SCHEDULE2_RECORD
import warnings
import inspect

import osconfeed

DB_NAME = 'data/schedule2_db'
CONFERENCE = 'conference.115'


class Record:
    def __init__(self, **kwargs):
        self.__dict__.update(kwargs)

    def __eq__(self, other):
        if isinstance(other, Record):
            return self.__dict__ == other.__dict__
        else:
            return NotImplemented
# END SCHEDULE2_RECORD


# BEGIN SCHEDULE2_DBRECORD
class MissingDatabaseError(RuntimeError):
    """Raised when a database is required but was not set."""


class DbRecord(Record):

    __db = None

    @staticmethod
    def set_db(db):
        DbRecord.__db = db

    @staticmethod
    def get_db():
        return DbRecord.__db

    @classmethod
    def fetch(cls, ident):
        db = cls.get_db()
        try:
            return db[ident]
        except TypeError:
            if db is None:
                msg = "database not set; call '{}.set_db(my_db)'"
                raise MissingDatabaseError(msg.format(cls.__name__))
            else:
                raise

    def __repr__(self):
        if hasattr(self, 'serial'):
            cls_name = self.__class__.__name__
            return '<{} serial={!r}>'.format(cls_name, self.serial)
        else:
            return super().__repr__()
# END SCHEDULE2_DBRECORD


# BEGIN SCHEDULE2_EVENT
class Event(DbRecord):

    @property
    def venue(self):
        key = 'venue.{}'.format(self.venue_serial)
        return self.__class__.fetch(key)

    @property
    def speakers(self):
        if not hasattr(self, '_speaker_objs'):
            spkr_serials = self.__dict__['speakers']
            fetch = self.__class__.fetch
            self._speaker_objs = [fetch('speaker.{}'.format(key))
                                  for key in spkr_serials]
        return self._speaker_objs

    def __repr__(self):
        if hasattr(self, 'name'):
            cls_name = self.__class__.__name__
            return '<{} {!r}>'.format(cls_name, self.name)
        else:
            return super().__repr__()
# END SCHEDULE2_EVENT


# BEGIN SCHEDULE2_LOAD
def load_db(db):
    raw_data = osconfeed.load()
    warnings.warn('loading ' + DB_NAME)
    for collection, rec_list in raw_data['Schedule'].items():
        record_type = collection[:-1]
        cls_name = record_type.capitalize()
        cls = globals().get(cls_name, DbRecord)
        if inspect.isclass(cls) and issubclass(cls, DbRecord):
            factory = cls
        else:
            factory = DbRecord
        for record in rec_list:
            key = '{}.{}'.format(record_type, record['serial'])
            record['serial'] = key
            db[key] = factory(**record)
# END SCHEDULE2_LOAD

示例 A-14 使用 py.test 测试示例 A-13。

示例 A-14　test_schedule2.py

import shelve
import pytest

import schedule2 as schedule


@pytest.yield_fixture
def db():
    with shelve.open(schedule.DB_NAME) as the_db:
        if schedule.CONFERENCE not in the_db:
            schedule.load_db(the_db)
        yield the_db


def test_record_attr_access():
    rec = schedule.Record(spam=99, eggs=12)
    assert rec.spam == 99
    assert rec.eggs == 12


def test_record_repr():
    rec = schedule.DbRecord(spam=99, eggs=12)
    assert 'DbRecord object at 0x' in repr(rec)
    rec2 = schedule.DbRecord(serial=13)
    assert repr(rec2) == "<DbRecord serial=13>"


def test_conference_record(db):
    assert schedule.CONFERENCE in db


def test_speaker_record(db):
    speaker = db['speaker.3471']
    assert speaker.name == 'Anna Martelli Ravenscroft'


def test_missing_db_exception():
    with pytest.raises(schedule.MissingDatabaseError):
        schedule.DbRecord.fetch('venue.1585')


def test_dbrecord(db):
    schedule.DbRecord.set_db(db)
    venue = schedule.DbRecord.fetch('venue.1585')
    assert venue.name == 'Exhibit Hall B'


def test_event_record(db):
    event = db['event.33950']
    assert repr(event) == "<Event 'There *Will* Be Bugs'>"


def test_event_venue(db):
    schedule.Event.set_db(db)
    event = db['event.33950']
    assert event.venue_serial == 1449
    assert event.venue == db['venue.1449']
    assert event.venue.name == 'Portland 251'


def test_event_speakers(db):
    schedule.Event.set_db(db)
    event = db['event.33950']
    assert len(event.speakers) == 2
    anna_and_alex = [db['speaker.3471'], db['speaker.5199']]
    assert event.speakers == anna_and_alex


def test_event_no_speakers(db):
    schedule.Event.set_db(db)
    event = db['event.36848']
    assert len(event.speakers) == 0