如何为测试目的对 sqlite 数据库进行猴子补丁？

Question

在 ORM.py 文件中：

from peewee import *
db = SqliteDatabase('database.db')

class Device(Model):
    uid = CharField(unique=True, max_length=17)

    class Meta:
        database = db

现在在 test.py 中，我想用 test.db 猴子补丁原始数据库 database.db

from _pytest.monkeypatch import MonkeyPatch

@pytest.fixture(scope="session")
def monkeysession(request):
    mp = MonkeyPatch()
    yield mp
    mp.undo()


@pytest.fixture(scope='session', autouse=True)
def create_db(monkeysession, request):
    monkeysession.setattr(ORM, 'db', SqliteDatabase('test.db'))

但我的错误（peewee.OperationalError: table "device" already exists）提示monkeypatch失败

Answer 1

http://docs.peewee-orm.com/en/latest/peewee/database.html#testing-peewee-applications

# tests.py
import unittest
from my_app.models import EventLog, Relationship, Tweet, User

MODELS = [User, Tweet, EventLog, Relationship]

# use an in-memory SQLite for tests.
test_db = SqliteDatabase(':memory:')

class BaseTestCase(unittest.TestCase):
    def setUp(self):
        # Bind model classes to test db. Since we have a complete list of
        # all models, we do not need to recursively bind dependencies.
        test_db.bind(MODELS, bind_refs=False, bind_backrefs=False)

        test_db.connect()
        test_db.create_tables(MODELS)

    def tearDown(self):
        # Not strictly necessary since SQLite in-memory databases only live
        # for the duration of the connection, and in the next step we close
        # the connection...but a good practice all the same.
        test_db.drop_tables(MODELS)

        # Close connection to db.
        test_db.close()

        # If we wanted, we could re-bind the models to their original
        # database here. But for tests this is probably not necessary.