pytest `AssertionError: View function mapping is overwriting an existing endpoint function:` flask-restful while registring blueprint
pytest `AssertionError: View function mapping is overwriting an existing endpoint function:` flask-restful while registring blueprint
问题如下，我创建了一个虚拟示例。文件夹结构是：
.
├── api_bp
│ └── __init__.py
├── app.py
├── pytest.ini
└── tests
├── conftest.py
├── __init__.py
├── test_todo1.py
└── test_todo2.py
文件夹api_bp里面的代码__init__.py:
# __init__.py
from flask import Blueprint
api_bp = Blueprint('api', __name__)
Flask 应用程序：
# app.py
from flask import Flask, Blueprint
from flask_restful import Api, Resource
class TodoItem(Resource):
def get(self, id):
return {'task': 'Say "Hello, World!"'}
def create_app():
"""Initialize the app. """
app = Flask(__name__)
from api_bp import api_bp
# api_bp = Blueprint('api', __name__)
api = Api(api_bp)
api.add_resource(TodoItem, '/todos/<int:id>')
app.register_blueprint(api_bp, url_prefix='/api')
return app
if __name__ == '__main__':
app = create_app()
app.run(debug=True)
出于测试目的，我有客户端 fixture 和两个针对不同待办事项的测试（我有意将其放入单独的模块）：
# conftest.py
import pytest
from app_factory import create_app
@pytest.fixture(scope='module')
def client():
flask_app = create_app()
testing_client = flask_app.test_client()
context = flask_app.app_context()
context.push()
yield testing_client
context.pop()
# test_todo1.py
import pytest
def test_todo2(client):
"""Test"""
response = client.get('/api/todos/1')
print(response)
assert response.status_code == 200
# test_todo2.py
import pytest
def test_todo2(client):
"""Test"""
response = client.get('/api/todos/2')
print(response)
assert response.status_code == 200
所以当我 运行 $ pytest -v 测试它时，我得到了以下错误：
AssertionError: View function mapping is overwriting an existing endpoint function: api.todoitem
发生这种情况是因为注册了蓝图。我想了解在 flask (flask-restful) 与 pytest 结合的情况下发生的魔法。因为如果我像这样定义我的 app.py 模块，它会成功通过测试：
# app.py
from flask import Flask, Blueprint
from flask_restful import Api, Resource
class TodoItem(Resource):
def get(self, id):
return {'task': 'Say "Hello, World!"'}
def create_app():
"""Initialize the app. """
app = Flask(__name__)
# note: I commented the line below and defined the blueprint in-place
# from api_bp import api_bp
api_bp = Blueprint('api', __name__)
api = Api(api_bp)
api.add_resource(TodoItem, '/todos/<int:id>')
app.register_blueprint(api_bp, url_prefix='/api')
return app
if __name__ == '__main__':
app = create_app()
app.run(debug=True)
$ pytest -v
tests/test_api1.py::test_todo2 PASSED [ 50%]
tests/test_api2.py::test_todo2 PASSED [100%]
或者，如果我不使用应用程序工厂，它也可以正常工作：
# app.py
from flask import Flask, Blueprint
from flask_restful import Api, Resource
app = Flask(__name__)
api_bp = Blueprint('api', __name__)
api = Api(api_bp)
class TodoItem(Resource):
def get(self, id):
return {'task': 'Say "Hello, World!"'}
api.add_resource(TodoItem, '/todos/<int:id>')
app.register_blueprint(api_bp, url_prefix='/api')
如果我将所有测试放在一个模块中，或者如果我先注册蓝图然后添加资源，也可以解决这个问题：
# app.py
...
def create_app():
"""Initialize the app. """
app = Flask(__name__)
from api_bp import api_bp
api = Api(api_bp)
app.register_blueprint(api_bp, url_prefix='/api')
api.add_resource(TodoItem, '/todos/<int:id>')
return app
...
谁知道这里发生了什么，可以解释一下magic？提前致谢。
所以问题的解释是，当 pytest 设置并在测试中使用客户端时，它会运行 create_app() 并在未在 app.py 中定义蓝图时尝试重用蓝图：
tests/test_api1.py::test_todo2 <flask.blueprints.Blueprint object at 0x7f04a8c9c610>
SETUP M client
tests/test_api1.py::test_todo2 (fixtures used: client)<Response streamed [200 OK]>
PASSED
TEARDOWN M client
tests/test_api2.py::test_todo2 <flask.blueprints.Blueprint object at 0x7f04a8c9c610>
SETUP M clientERROR
TEARDOWN M client
可以通过以下方式解决：
# api_bp/__init__.py
from flask import Blueprint
get_blueprint = lambda: Blueprint('api', __name__)
并使用：
def create_app():
"""Initialize the app. """
app = Flask(__name__)
from api_bp import get_blueprint
api_bp = get_blueprint()
api = Api(api_bp)
api.add_resource(TodoItem, '/todos/<int:id>')
app.register_blueprint(api_bp, url_prefix='/api')
return app
因此，解决此类问题的最简单方法是使用适当的 pytest 作用域（而不是 'module'）：
@pytest.fixture(scope='session')
def client():
...
更新：
此方法不适用于定义如下管理命令：
class Test(Command):
def run(self):
"""Runs the tests."""
pytest.main(['-s', '-v', './tests'])
manager.add_command('test', Test) # run the tests
使用 python app.py test 你会得到与前面示例相同的错误。有关详细信息，请阅读以下 link 中的 'Note:' 部分：https://docs.pytest.org/en/latest/usage.html#calling-pytest-from-python-code
问题如下，我创建了一个虚拟示例。文件夹结构是：
.
├── api_bp
│ └── __init__.py
├── app.py
├── pytest.ini
└── tests
├── conftest.py
├── __init__.py
├── test_todo1.py
└── test_todo2.py
文件夹api_bp里面的代码__init__.py:
# __init__.py
from flask import Blueprint
api_bp = Blueprint('api', __name__)
Flask 应用程序：
# app.py
from flask import Flask, Blueprint
from flask_restful import Api, Resource
class TodoItem(Resource):
def get(self, id):
return {'task': 'Say "Hello, World!"'}
def create_app():
"""Initialize the app. """
app = Flask(__name__)
from api_bp import api_bp
# api_bp = Blueprint('api', __name__)
api = Api(api_bp)
api.add_resource(TodoItem, '/todos/<int:id>')
app.register_blueprint(api_bp, url_prefix='/api')
return app
if __name__ == '__main__':
app = create_app()
app.run(debug=True)
出于测试目的，我有客户端 fixture 和两个针对不同待办事项的测试（我有意将其放入单独的模块）：
# conftest.py
import pytest
from app_factory import create_app
@pytest.fixture(scope='module')
def client():
flask_app = create_app()
testing_client = flask_app.test_client()
context = flask_app.app_context()
context.push()
yield testing_client
context.pop()
# test_todo1.py
import pytest
def test_todo2(client):
"""Test"""
response = client.get('/api/todos/1')
print(response)
assert response.status_code == 200
# test_todo2.py
import pytest
def test_todo2(client):
"""Test"""
response = client.get('/api/todos/2')
print(response)
assert response.status_code == 200
所以当我 运行 $ pytest -v 测试它时，我得到了以下错误：
AssertionError: View function mapping is overwriting an existing endpoint function: api.todoitem
发生这种情况是因为注册了蓝图。我想了解在 flask (flask-restful) 与 pytest 结合的情况下发生的魔法。因为如果我像这样定义我的 app.py 模块，它会成功通过测试：
# app.py
from flask import Flask, Blueprint
from flask_restful import Api, Resource
class TodoItem(Resource):
def get(self, id):
return {'task': 'Say "Hello, World!"'}
def create_app():
"""Initialize the app. """
app = Flask(__name__)
# note: I commented the line below and defined the blueprint in-place
# from api_bp import api_bp
api_bp = Blueprint('api', __name__)
api = Api(api_bp)
api.add_resource(TodoItem, '/todos/<int:id>')
app.register_blueprint(api_bp, url_prefix='/api')
return app
if __name__ == '__main__':
app = create_app()
app.run(debug=True)
$ pytest -v
tests/test_api1.py::test_todo2 PASSED [ 50%]
tests/test_api2.py::test_todo2 PASSED [100%]
或者，如果我不使用应用程序工厂，它也可以正常工作：
# app.py
from flask import Flask, Blueprint
from flask_restful import Api, Resource
app = Flask(__name__)
api_bp = Blueprint('api', __name__)
api = Api(api_bp)
class TodoItem(Resource):
def get(self, id):
return {'task': 'Say "Hello, World!"'}
api.add_resource(TodoItem, '/todos/<int:id>')
app.register_blueprint(api_bp, url_prefix='/api')
如果我将所有测试放在一个模块中，或者如果我先注册蓝图然后添加资源，也可以解决这个问题：
# app.py
...
def create_app():
"""Initialize the app. """
app = Flask(__name__)
from api_bp import api_bp
api = Api(api_bp)
app.register_blueprint(api_bp, url_prefix='/api')
api.add_resource(TodoItem, '/todos/<int:id>')
return app
...
谁知道这里发生了什么，可以解释一下magic？提前致谢。
所以问题的解释是，当 pytest 设置并在测试中使用客户端时，它会运行 create_app() 并在未在 app.py 中定义蓝图时尝试重用蓝图：
tests/test_api1.py::test_todo2 <flask.blueprints.Blueprint object at 0x7f04a8c9c610>
SETUP M client
tests/test_api1.py::test_todo2 (fixtures used: client)<Response streamed [200 OK]>
PASSED
TEARDOWN M client
tests/test_api2.py::test_todo2 <flask.blueprints.Blueprint object at 0x7f04a8c9c610>
SETUP M clientERROR
TEARDOWN M client
可以通过以下方式解决：
# api_bp/__init__.py
from flask import Blueprint
get_blueprint = lambda: Blueprint('api', __name__)
并使用：
def create_app():
"""Initialize the app. """
app = Flask(__name__)
from api_bp import get_blueprint
api_bp = get_blueprint()
api = Api(api_bp)
api.add_resource(TodoItem, '/todos/<int:id>')
app.register_blueprint(api_bp, url_prefix='/api')
return app
因此，解决此类问题的最简单方法是使用适当的 pytest 作用域（而不是 'module'）：
@pytest.fixture(scope='session')
def client():
...
更新：
此方法不适用于定义如下管理命令：
class Test(Command):
def run(self):
"""Runs the tests."""
pytest.main(['-s', '-v', './tests'])
manager.add_command('test', Test) # run the tests
使用 python app.py test 你会得到与前面示例相同的错误。有关详细信息，请阅读以下 link 中的 'Note:' 部分：https://docs.pytest.org/en/latest/usage.html#calling-pytest-from-python-code