Mock the database in the unit test suite

[dstufft]

No description provided.

[ncoghlan]

A potentially simpler approach is to use an in-memory sqlite database for
unit testing.

[dstufft]

I don't plan on keeping compatibility with SQLite. Right now there is but once PyPI legacy is gone and I can modify the schema I plan to take advantage of PostgreSQL's advanced capabilities.

This is just for the unit tests though, the functional tests (which will test high level features/user stories) will still be required to be backed by a real database.

[ncoghlan]

I suspect (but can't prove) that an sqlite compatible subset of the schema
will be easier to maintain than a lot of database mocks.

[dstufft]

Possibly. I'm not worried about the speed of PostgreSQL mostly that it's annoying to have to type out the command. If I can't mock it then I'll probably just leave it as is.

[alex]

Not mocks, fakes! Verified fakes ideally :) /cc @dreid

On Sun, Oct 20, 2013 at 3:08 PM, Donald Stufft [email protected]:

Possibly. I'm not worried about the speed of PostgreSQL mostly that it's
annoying to have to type out the command. If I can't mock it then I'll
probably just leave it as is.

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[dstufft]

Well I'd want to verify that the method is calling the execute method with a particular query, so that would be a mock would it not?

[alex]

Oh, if your'e going to do it that way, then yes it's a mock. I think having
a verified fake for the models layer is a saner approach.

On Sun, Oct 20, 2013 at 3:35 PM, Donald Stufft [email protected]:

Well I'd want to verify that the method is calling the execute method with
a particular query, so that would be a mock would it not?

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[dstufft]

Hmm, well I have functions like this: https://github.com/dstufft/warehouse/blob/master/warehouse/packaging/models.py#L35-L39

And I need to test them, currently I test them by starting a transaction, filling in some data, testing the return of that function, then rolling back the transaction. My thought was to just replace the execute function with a Mock and verify that the query matches. How would your way work?

[alex]

Basically you replace the models layer with a fake object that just keeps
the "database" in a dictionary.

On Sun, Oct 20, 2013 at 3:37 PM, Donald Stufft [email protected]:

Hmm, well I have functions like this:
https://github.com/dstufft/warehouse/blob/master/warehouse/packaging/models.py#L35-L39

And I need to test them, currently I test them by starting a transaction,
filling in some data, testing the return of that function, then rolling
back the transaction. My thought was to just replace the execute function
with a Mock and verify that the query matches. How would your way work?

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[dstufft]

But how do I test the models layer itself?

[dstufft]

I'm already stubbing out the models layer outside of tests of the model layer.

[alex]

Ah, I'd test the models layer against the real DB; if you do anything
besides trivial queries testing the DB layer with mocks is just a mess, how
do you verify that:
https://bitbucket.org/pypa/pypi/src/e5fae2ee665bd38b51ff77026ff304e70dfc229c/store.py?at=default#cl-1154is
correct witha mock?

Alex

On Sun, Oct 20, 2013 at 3:38 PM, Donald Stufft [email protected]:

But how do I test the models layer itself?

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[dstufft]

Hrm, I suppose complex queries would be a problem :/

[dstufft]

Ok i've been sufficiently convinced.