Allow disabling of all migrations during tests

[Markus Holtermann]

As an extension to #24919 a setting DATABASE['TEST']['MIGRATE'] = False should disable all migrations on that particular database. This can be done by hooking into django.db.migrations.loader.MigrationLoader.migrations_module() and returning None.

[Wiktor]

​https://github.com/django/django/pull/5601

[Berker Peksag]

Updated PR: ​https://github.com/django/django/pull/6323

[Markus Holtermann <info@…>]

In 157d7f1f:

Fixed #25388 -- Added an option to allow disabling of migrations during test database creation

[Tim Graham <timograham@…>]

In 14e6823:

Refs #25388 -- Used in-memory database in test_disable_migrations.

[Tim Graham]

As described in #26838, this feature doesn't seem to work as migrations are disabled in more than just tests when setting DATABASES['default']['TEST'] = {'MIGRATE': False}. If this requires more than a trivial fix, let's remove the feature from 1.10.

[Tim Graham <timograham@…>]

In 944e66cb:

Reverted "Fixed #25388 -- Added an option to allow disabling of migrations during test database creation"

This reverts commit 157d7f1f1de4705daddebb77f21bd7097a74513d since it
disables migrations all the time, not just during tests.

[Tim Graham <timograham@…>]

In 5c56ce7:

[1.10.x] Reverted "Fixed #25388 -- Added an option to allow disabling of migrations during test database creation"

This reverts commit 157d7f1f1de4705daddebb77f21bd7097a74513d since it
disables migrations all the time, not just during tests.

Backport of 944e66cb1db6614ef0644b9030dd1d75e950767c from master

[Berker Peksag]

Here's a WIP concept: ​https://github.com/django/django/compare/master...berkerpeksag:25388-migrate-false-v2 Added an attribute to BaseDatabaseWrapper to be used during the creation of the test database. It's probably not the best way to solve the problem, but it prevents the bug described in #26838.

[Eyad Toma]

Assigned to myself due to inactivity for 2 months.
Working on top of Berker's solution.

[Eyad Toma]

Patch submitted ​https://github.com/django/django/pull/7499

it wasn't possible to write tests because setting "_run_in_test_case" on the connection only works before creating the test DB.
I tried override setting and creating "ConnectionHandler" but failed because of the reason above.

[Tobias McNulty]

Reviewing at DUTH sprint

[Tobias McNulty]

Another option (which I prefer over the current implementation, the more I think about it) would be to add a new option to the migrate management command that would *only* run syncdb (i.e., it would pass an argument into the MigrationLoader telling it to do what you do now in the above PR). This seems less magical than the current implementation as it would facilitate passing the option down through the stack rather than setting it on a global variable (the db connection).

[Tobias McNulty]

Another question: What about the currently documented method of suppressing migrations is insufficient? I.e., would simply improving that documentation be a suitable alternative to this ticket?

[Markus Holtermann]

Replying to Tobias McNulty:

Another option (which I prefer over the current implementation, the more I think about it) would be to add a new option to the migrate management command that would *only* run syncdb

I don't like that option. syncdb in it's current form will go away in some way or another in the future. migrate doesn't run syncdb automatically anymore unless explicitly said otherwise.

[Berker Peksag]

Assigned to myself due to inactivity for 2 months.

Thank you for working on this, Eyad. By the way, the inactivity was mainly due to the lack of feedback. I'm not very experienced on this part of Django and I wasn't sure that my solution is a good one. So it would be great if you could get some feedback from the domain experts :)

[Tim Graham]

My take on the motivation of this ticket is to ease the boilerplate of setting MIGRATIONS_MODULES['app'] = None for all apps in a test settings file. I think it has some value if a nice solution is found.

[Jaap Roes]

This would be a very welcome addition to Django. In the mean time, we've been adding the following to all our projects test_settings to speed up testing:

class NoMigrations:
    """Disable migrations for all apps"""
    def __getitem__(self, item):
        return None

    def __contains__(self, item):
        return True

MIGRATION_MODULES = NoMigrations()

[Jon Dufresne]

I took a new approach in PR ​https://github.com/django/django/pull/12062

[Mariusz Felisiak <felisiak.mariusz@…>]

In f5ebdfce:

Fixed #25388 -- Added an option to allow disabling of migrations during test database creation.

[Mariusz Felisiak <felisiak.mariusz@…>]

In a69c4d62:

Refs #25388 -- Corrected value of TEST MIGRATE setting in MIGRATION_MODULES docs.