在Flask-SQLAlchemy中隔离py.test数据库会话 [英] Isolating py.test DB sessions in Flask-SQLAlchemy

问题描述

我试图用Flask-SQLAlchemy构建一个Flask应用程序;我使用pytest来测试数据库。其中一个问题似乎是在不同的测试之间创建隔离的数据库会话。

我编写了一个最小的完整示例来突出显示问题，注意 test_user_schema1（）和 test_user_schema2（）是相同的。 code> test_db.py

  from models import User 
 
 def test_user_schema1（session）：
 person_name ='Fran Clan'
 uu = User（name = person_name）
 session.add（uu）
 session.commit（）
 
 assert uu.id == 1 
 assert uu.name == person_name 
 
 def test_user_schema2（session）：
 person_name ='Stan Clan'
 uu = User（name = person_name）
 session.add（uu）
 session.commit（）
 
 assert uu.id == 1 
 assert uu .name == person_name 
  

如果db在我的测试之间是真正的隔离，那么这两个测试都应该通过。然而，最后一次测试总是失败，因为我还没有找到一个方法来使db会话正确回滚。

conftest.py 使用以下关于我在中看到的，但是这个夹具代码打破了，因为它显然不干'b
$ b

  @ pytest.yield_fixture（scope ='function'）
 def session （app，db）：
 connection = db.engine.connect（）
 transaction = connection.begin（）
 
 #options = dict（bind = connection，binds = { }）
 options = dict（bind = connection）
 session = db.create_scoped_session（options = options）
 
 yield session 
 
＃ 
 transaction.rollback（）
 connection.close（）
 session.remove（）
  

就这个问题而言，我建立了 a gist ，其中包含所有需要重现的内容;你可以用 git clone克隆https://gist.github.com/34fa8d274fc4be240933.git 。

I我使用下列软件包...

  Flask == 0.10.1 
 Flask-Bootstrap == 3.3.0.1 
 Flask-Migrate == 1.3.0 
 Flask-Moment == 0.4.0 
 Flask-RESTful == 0.3.1 
 Flask-Script == 2.0.5 
 Flask-SQLAlchemy == 2.0 
 Flask-WTF == 0.11 
 itsdangerous == 0.24 
 pytest == 2.6.4 
 Werkzeug == 0.10.1 
  

两个问题：

1. 为什么现状被破坏？
   
2. 我怎样才能解决这个问题？

解决方案

据

commit（）用于提交当前事务。它总是事先发送flush（）以将剩余的状态清除到数据库。这与自动刷新设置无关。 ....

所以 transaction.rollback（）在会话夹具功能不会生效，因为交易已经提交。

---

2。

将夹具的范围更改为 function 而不是 session ，这样db每次被清除。 p>

  @ pytest.yield_fixture（scope ='function'）
 def app（request）：
 ... 
 $ b $ pytest.yield_fixture（scope ='function'）
 def db（app，request）：
 ... 
  

---

顺便说一句，如果你使用内存中的sqlite数据库，你不需要删除数据库文件，它会更快：

pre $ DB $ ='sqlite：//'＃SQLite：内存：​​数据库


$ pytest.yield_fixture（scope ='function'）
def db（app，request）：
_db.app = app
_db .create_all（）
yield _db
_db.drop_all（）

I'm trying to build a Flask app with Flask-SQLAlchemy; I use pytest to test the DB. One of the problems seems to be creating isolated DB sessions between different tests.

I cooked up a minimal, complete example to highlight the problem, note that test_user_schema1() and test_user_schema2() are the same.

Filename: test_db.py

from models import User

def test_user_schema1(session):
    person_name = 'Fran Clan'
    uu = User(name=person_name)
    session.add(uu)
    session.commit()

    assert uu.id==1
    assert uu.name==person_name

def test_user_schema2(session):
    person_name = 'Stan Clan'
    uu = User(name=person_name)
    session.add(uu)
    session.commit()

    assert uu.id==1
    assert uu.name==person_name

If the db is truly isolated between my tests, both tests should pass. However, the last test always fails, because I haven't found a way to make db sessions rollback correctly.

conftest.py uses the following based on what I saw in Alex Michael's blog post, but this fixture code breaks because it apparently doesn't isolate the db sessions between fixtures.

@pytest.yield_fixture(scope='function')
def session(app, db):
    connection = db.engine.connect()
    transaction = connection.begin()

    #options = dict(bind=connection, binds={})
    options = dict(bind=connection)
    session = db.create_scoped_session(options=options)

    yield session

    # Finalize test here
    transaction.rollback()
    connection.close()
    session.remove()

For the purposes of this question, I built a gist, which contains all you need to reproduce it; you can clone it with git clone https://gist.github.com/34fa8d274fc4be240933.git.

I am using the following packages...

Flask==0.10.1
Flask-Bootstrap==3.3.0.1
Flask-Migrate==1.3.0
Flask-Moment==0.4.0
Flask-RESTful==0.3.1
Flask-Script==2.0.5
Flask-SQLAlchemy==2.0
Flask-WTF==0.11
itsdangerous==0.24
pytest==2.6.4
Werkzeug==0.10.1

Two questions:

1. Why is status quo broken? This same py.test fixture seemed to work for someone else.
2. How can I fix this to work correctly?

解决方案

1.

According to Session Basics - SQLAlchemy documentation:

commit() is used to commit the current transaction. It always issues flush() beforehand to flush any remaining state to the database; this is independent of the "autoflush" setting. ....

So transaction.rollback() in session fixture function does not take effect, because the transaction is already committed.

---

2.

Change scope of fixtures to function instead of session so that db is cleared every time.

@pytest.yield_fixture(scope='function')
def app(request):
    ...

@pytest.yield_fixture(scope='function')
def db(app, request):
    ...

---

BTW, If you use in-memory sqlite database, you don't need to delete the db files, and it will be faster:

DB_URI = 'sqlite://'  # SQLite :memory: database

...

@pytest.yield_fixture(scope='function')
def db(app, request):
    _db.app = app
    _db.create_all()
    yield _db
    _db.drop_all()

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