Hi Tim,
I can have a look, but I can't be certain about hitting any deadlines. I do
want to get that deprecation in, though...
Did you want it with a view to us being able to drop that in for tests
rather than making migrations for every test app, I presume?
Andrew
On Fri, Dec 19, 2014 at 3:06 PM, Tim Graham <timogra...@gmail.com> wrote:
>
> Andrew, I've thought of something similar to the in-memory migrations idea
> you've proposed. It would be great not to have to add and maintain
> migrations for all of the apps in Django's test suite. Do you think you
> might be able to investigate this solution in the next month or so before
> 1.8 alpha? I think we need a solution in 1.8 if we are to complete #22340 -
> Legacy
> Table Creation Methods Not Properly Deprecated (otherwise, we can again
> postpone that deprecation).
>
> On Friday, December 19, 2014 8:17:05 AM UTC-5, Andrew Godwin wrote:
>>
>> I agree that migrations are slower than syncdb - that's perhaps the only
>> thing worse about them - but the reason we plan to deprecate the other
>> methods is code simplicity; migrations does not share almost any code with
>> the old DatabaseCreation backends, and if we don't deprecate it we're going
>> to end up maintaining two creation backends for every database driver,
>> which isn't going to go well.
>>
>> There's perhaps something to be said for an option where tests make an
>> in-memory set of migrations from the autodetector and an empty state and
>> run them immediately - somewhat replicating the syncdb process while still
>> using the same code paths - but I haven't had the time to investigate how
>> well this would work yet (there are some migration decisions that would
>> need defaults inserted).
>>
>> I think the end result would be an alternative test runner that you could
>> switch to if you wanted this behaviour (and a mixin with the actual logic
>> or something similar so it's easy to incorporate into other test runners).
>>
>> Andrew
>>
>> On Wed, Dec 17, 2014 at 6:59 PM, <c...@epantry.com> wrote:
>>
>>> At the risk of reviving an old topic, I wanted to add one significant
>>> point in favor of (and mitigation for) running tests with migrations
>>> disabled: Speed.
>>>
>>> Creating a test DB in sqlite for our project (~100 database tables)
>>> takes approximately 1-2 minutes on most developer machines. 1-2 minutes
>>> of idle time to run any test was just unacceptable so we disabled
>>> migrations by setting fake migrations in MIGRATION_MODULES and brought the
>>> test DB creation time down to about 5 seconds (!!).
>>>
>>> However the risk of committing invalid code because someone forgot to
>>> makemigrations is real. We've addressed it by only overriding migrations on
>>> our local test settings and still having migrations run on our CI server.
>>> We have our CI server use settings.test, while developers running tests on
>>> their local machine use settings.test_local which is just:
>>>
>>> from settings.test import *
>>>
>>> MIGRATION_MODULES = ((app, '%s.fake_migrations' % app) for app in
>>> INSTALLED_APPS)
>>>
>>>
>>> This seems to get us the best of both worlds. I was surprised to read
>>> through this thread and not see other mentions of the performance
>>> implications of running migrations on every test run. I'd be curious to
>>> hear if this has been a bottleneck for other teams.
>>>
>>> -Chris
>>>
>>> On Tuesday, March 25, 2014 10:21:51 AM UTC-7, Bernie Sumption wrote:
>>>
>>>> Hi Django devs,
>>>>
>>>> I've just started a new project in 1.7b, and the development experience
>>>> working with unit tests on models is more complicated than it was in 1.6.
>>>> It's all down to how the throwaway test databases are created. In 1.6, the
>>>> create_test_db function "Creates a new test database and runs syncdb
>>>> against it." In 1.7, it runs "migrate".
>>>>
>>>> While generally speaking, migrate is the new syncdb, this behaviour is
>>>> not ideal for tests. In 1.6 "syncdb" created a database reflecting the
>>>> current state of the models in models.py. "migrate" creates a database
>>>> reflecting the state of the models at the last time makemigrations was run.
>>>> If you're doing TDD and constantly making small changes to your models then
>>>> runnning unit tests, you have to run makemigrations before each test run to
>>>> get your tests to work. You therefore end up with many tiny migration files
>>>> representing the minute-by-minute history of development.
>>>>
>>>> I came up with a pretty effective workaround that is working for me,
>>>> but I thought I'd post this here as others are sure to encounter this
>>>> issue, and I think that it makes more sense for the behaviour produced by
>>>> this workaround to be the default for running tests.
>>>>
>>>> If makemigrations has not yet been run, the "migrate" command treats an
>>>> app as unmigrated, and creates tables directly from the models just like
>>>> syncdb did in 1.6. I defined a new settings module just for unit tests
>>>> called "settings_test.py", which imports * from the main settings module
>>>> and adds this line:
>>>>
>>>> MIGRATION_MODULES = {"myapp": "myapp.migrations_not_used_in_tests"}
>>>>
>>>> Then I run tests like this:
>>>>
>>>> DJANGO_SETTINGS_MODULE="myapp.settings_test" python manage.py test
>>>>
>>>> This fools migrate into thinking that the app is unmigrated, and so
>>>> every time a test database is created it reflects the current structure of
>>>> models.py.
>>>>
>>>> So my feature request is as follows:
>>>>
>>>> If the new behaviour is by design and considered desirable, then it is
>>>> a big change from the previous version and should be prominently documented
>>>> in the migrations and testing pages, along with the workaround. I'm happy
>>>> to write this documentation if that's the way you want to go.
>>>>
>>>> However, if the new behaviour is not by design but just a by-product of
>>>> the new migrations feature, I suggest making the workaround the default
>>>> behaviour. I don't (yet!) know enough about Django internals to volunteer
>>>> for this however.
>>>>
>>>> Thanks for your time,
>>>>
>>>> Bernie :o)
>>>>
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