Regarding the Postgres in production and SQLite in testing differences, we've previously had problems with Postgres's Array - which doesn't exist in SQLite. Also watch out for the differences between how they interpret GROUP BY and DISTINCT - I've had this problem only today where a complicated query I wrote and tested in unittest (SQLite) doesn't work on development localhost (Postgres).
Alex, thanks very much for this blog post - very helpful. I was just talking about this strategy with my colleague today. I've previously switch over to Postgres in test to address problems with Array - however I had to bring the project back over again because of speed issues - it was taking far too long to do a set up and tear down of the DB for each test. It looks like your solution will be much quicker than our previous one because of your strategy with transactions. Cheers, James On Wednesday, September 11, 2013 6:12:07 PM UTC+1, Alex Grönholm wrote: > > I wrote a blog post on this very topic recently: > http://alextechrants.blogspot.fi/2013/08/unit-testing-sqlalchemy-apps.html > > > tiistai, 10. syyskuuta 2013 19.43.35 UTC+3 Toph Burns kirjoitti: >> >> Could you use an in-memory, sqlite db for your testing? For our >> applications, we have an initialization function that loads the database >> connection strings from a config (.ini) file, passing those on to >> create_engine. In production it's a postgresql connection string, for >> test, it's a "sqlite:///:memory:' >> >> >> Toph Burns | Software Engineer >> 5885 Hollis St. Suite 100 >> Emeryville, CA 94608 >> 510-597-4797 >> bu...@amyris.com >> ------------------------------ >> *From:* sqlal...@googlegroups.com [sqlal...@googlegroups.com] on behalf >> of Michel Albert [exh...@gmail.com] >> *Sent:* Tuesday, September 10, 2013 1:46 AM >> *To:* sqlal...@googlegroups.com >> *Subject:* [sqlalchemy] Unit testing, mocking and dependency injection >> with SA Declarative. >> >> I am trying to wrap my head around how to do Dependency Injection with >> SQLAlchemy and I am walking in circles. >> >> I want to be able to mock out SA for most of my tests. I trust SA and >> don't want to test serialisation into the DB. I just want to test my own >> code. So I was thinking to do dependency injection, and mock out SA during >> testing. >> >> But I don't know what to mock out, how and when to set up the session >> properly, without doing it at the module level (which causes unwanted >> side-effects only by importing the module). >> >> The only solution which comes to mind is to have one "singleton" which >> deals with that. But that feels very unpythonic to me and I am wondering if >> there's a better solution. >> >> I also saw that "create_engine" has an optional "module" kwarg, which I >> could mock out. But then SA begins complaining that the return types are >> not correct. And I don't want to specify return values for every possible >> db-module call. That's way out of scope of my tests. I am not calling >> anything on the db-module. That's SA's job, and, as said, I already trust >> SA. >> >> Whenever I work on this I always run into the session_maker >> initialisation as well. The examples to this on the module level, which I >> really make me feel uneasy. >> >> Any tips? Just prodding myself in the right direction might help me out >> enough. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sqlalchemy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to sqlalchemy+...@googlegroups.com. >> To post to this group, send email to sqlal...@googlegroups.com. >> Visit this group at http://groups.google.com/group/sqlalchemy. >> For more options, visit https://groups.google.com/groups/opt_out. >> > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/groups/opt_out.
