Can someone show me how to write unit tests for sqlalchemy model I created using nose.
I just need one simple example.
Thanks.
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3Be more specific: do you need help in how to setup nose? or how to test a model?van– van2009-05-28 12:59:41 +00:00Commented May 28, 2009 at 12:59
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2 Answers
You can simply create an in-memory SQLite database and bind your session to that.
Example:
from db import session # probably a contextbound sessionmaker
from db import model
from sqlalchemy import create_engine
def setup():
engine = create_engine('sqlite:///:memory:')
session.configure(bind=engine)
# You probably need to create some tables and
# load some test data, do so here.
# To create tables, you typically do:
model.metadata.create_all(engine)
def teardown():
session.remove()
def test_something():
instances = session.query(model.SomeObj).all()
eq_(0, len(instances))
session.add(model.SomeObj())
session.flush()
# ...
4 Comments
van
Great answer! I think you need to call
create_all on the MetaData object to actually create tables. Also if db-vendor specific data types are used, then some of the DDLs may not run.
codeape
Good points. I updated the example to show a call to create_all.
Michael Robellard
This is a horrible answer if SQLLite is not your production database. Never test with a different database than the one you are using in production. They will have lots of differences and you are setting yourself up for a disaster.
codeape
You could of course use a Postgresql, MySQL, etc. database server for executing the tests against. The setup and teardown methods above would possibly be a bit different then, you probably would do a CREATE DATABASE in setup and a DROP DATABASE in teardown. I have seldom had any problems by switching DB backends using SQLAlchemy. I routinely do automatic tests against SQLite and run the prod system on Postg, MySQL or MSSQL. One system I developed, we did unit testing against SQLite, integration testing on Linux/Postgres and the production system was Win/MSSQL. No changes in DB access code.
Check out the fixture project. We used nose to test that and it's also a way to declaratively define data to test against, there will be some extensive examples for you to use there!
See also fixture documentation.
