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On Tue, Jul 01, 2014 at 03:21:06PM -0500, Matt Riedemann wrote:
> As part of the enforce-unique-instance-uuid-in-db blueprint [1] I'm writing
> a script to scan the database and find any NULL instance_uuid records that
> will cause the new database migration to fail so that operators can run this
> before they run the migration, otherwise the migration blocks if these types
> of records are found.
> 
> I have the script written [2], but wanted to also write unit tests for it. I
> guess I assumed the script would go under nova/tools/db like the
> schema_diff.py script, but I'm not sure how to unit test anything outside of
> the nova/nova tree.
> 
> Nova's testr configuration is only discovering tests within nova/tests [3].
> But I don't think I can put the unit tests under nova/tests and then import
> the module from nova/tools.

So we hit a similar issue in tempest when we wanted to unit test some utility
scripts in tempest/tools. Changing the discovery path to find tests outside of
nova/tests is actually a pretty easy change[4], but I don't think that will solve
the use case with tox. What happened when we tried to do this in tempest use
case was that when the project was getting installed the tools dir wasn't
included so when we ran with tox it couldn't find the files we were trying to
test. The solution we came up there was to put the script under the tempest
namespace and add unit tests in tempest/tests. (we also added an entry point for
the script to expose it as a command when tempest was installed)

> 
> So I'm a bit stuck.  I could take the easy way out and just throw the script
> under nova/db/sqlalchemy/migrate_repo and put my unit tests under
> nova/tests/db/, and I'd also get pep8 checking with that, but that doesn't
> seem right - but I'm also possibly over-thinking this.
> 
> Anyone else have any ideas?

I think it really comes down to how you want to present the utility to the end
users. To enable unit testing it, it's just easier to put it in the nova
namespace. I couldn't come up with a good way to get around the
install/namespace issue. (maybe someone else who is more knowledgeable here has
a good way to get around this) So then you can symlink it to the tools dir or
add an entry point (or bake it into nova-manage) to make it easy to find. I
think the issue with putting it in nova/db/sqlalchemy/migrate_repo is that it's
hard to find.

> 
> [1] https://blueprints.launchpad.net/nova/+spec/enforce-unique-instance-uuid-in-db
> [2] https://review.openstack.org/#/c/97946/
> [3] http://git.openstack.org/cgit/openstack/nova/tree/.testr.conf#n5
[4] http://git.openstack.org/cgit/openstack/tempest/tree/tempest/test_discover/test_discover.py

-Matt Treinish
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