如何在Flask-SqlAlchemy中模拟<ModelClass>.query.filter_by()
如何在Flask-SqlAlchemy中模拟<ModelClass>.query.filter_by()
提问于 2017-02-27 17:26:31
简而言之
在Flask-SqlAlchemy中测试模型类时，我们如何模拟方法.query.filter_by()以便返回模拟的模型对象列表？
完整详细信息
假设我们有一个模型类，如下所示
from flask.ext.sqlalchemy import SQLAlchemy
db = SQLAlchemy()
class SomeModel(db.Model):
# more column mapping and methods go here然后在我们的Flask代码中调用
SomeModel.query.filter_by(...)在我们的测试代码中，使用带有mocking的Python unittest模型，我们希望模拟filter_by()调用，以便它返回我们设计的测试用例下的模型对象列表。
我们怎样才能做到这一点？
附注：
我在谷歌上搜索只能找到this related post；尽管在课程开始时应用@patch("flask_sqlalchemy.SignallingSession", autospec=True)对我不起作用。
我还尝试像下面的代码片段那样模拟该函数
@patch('app.model.some_model.SomeModel.query.filter_by')
def test_some_case(self, filterbyMOCK):
# more test logic goes here并且代码在启动时立即出现错误
RuntimeError: application not registered on db instance and no application bound to current contextPyCharm集成开发环境中的完整错误如下所示。
Traceback (most recent call last):
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/mock/mock.py", line 1297, in patched
arg = patching.__enter__()
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/mock/mock.py", line 1353, in __enter__
self.target = self.getter()
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/mock/mock.py", line 1523, in <lambda>
getter = lambda: _importer(target)
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/mock/mock.py", line 1210, in _importer
thing = _dot_lookup(thing, comp, import_path)
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/mock/mock.py", line 1197, in _dot_lookup
return getattr(thing, comp)
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/flask_sqlalchemy/__init__.py", line 428, in __get__
return type.query_class(mapper, session=self.sa.session())
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/scoping.py", line 78, in __call__
return self.registry()
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/sqlalchemy/util/_collections.py", line 990, in __call__
return self.registry.setdefault(key, self.createfunc())
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/flask_sqlalchemy/__init__.py", line 136, in __init__
self.app = db.get_app()
File "/home/namgivu/NN/code/someproject-cloud/venv/local/lib/python2.7/site-packages/flask_sqlalchemy/__init__.py", line 809, in get_app
raise RuntimeError('application not registered on db '
RuntimeError: application not registered on db instance and no application bound to current contextStack Overflow用户
回答已采纳
发布于 2017-02-27 17:34:43
您必须模拟整个映射器类；访问映射器上的query属性会导致会话加载：
@patch('app.model.some_model.SomeModel')
def test_some_case(self, some_model_mock):
filter_by_mock = some_model_mock.query.filter_by
# more test logic goes here这是因为.query属性是一个描述符对象；访问它会触发到会话的绑定。
另一种方法是模拟_QueryProperty.__get__ method (它支持.query属性)；只有在必须使用实际的SomeModel实例进行测试时才使用此方法：
@patch('flask_sqlalchemy._QueryProperty.__get__')
def test_some_case(self, query_property_getter_mock):
filter_by_mock = query_property_getter_mock.return_value.filter_by
# more test logic goes here演示：
>>> from flask_sqlalchemy import SQLAlchemy
>>> db = SQLAlchemy()
>>> class SomeModel(db.Model):
... id = db.Column(db.Integer, primary_key=True)
...
>>> from unittest import mock
>>> with mock.patch('__main__.SomeModel') as model_mock:
... filter_by = model_mock.query.filter_by
... SomeModel.query.filter_by(SomeModel.id == 'foo')
...
<MagicMock name='SomeModel.query.filter_by()' id='4438980312'>
>>> with mock.patch('flask_sqlalchemy._QueryProperty.__get__') as query_property_getter_mock:
... filter_by_mock = query_property_getter_mock.return_value.filter_by
... SomeModel.query.filter_by(SomeModel.id == 'foo')
...
<MagicMock name='__get__().filter_by()' id='4439035184'>页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/42482021
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