#29225: The non-test sqlite database can be easily destroyed during tests
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Reporter: gh720 | Owner: nobody
Type: Bug | Status: new
Component: Testing framework | Version: 1.11
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Description changed by gh720:
Old description:
> I don't know if it is a bug or just a nasty feature, that appears to be
> undocumented, or a well known caveat that I don't know about.
>
> With a few seemingly innocent steps you can get your working sqlite
> database destroyed during tests.
> Suppose you hold a few database configs in settings.DATABASES:
>
> {{{
> DATABASES = { 'sqlite1': { ... }, 'sqlite2': { ... } }
> }}}
>
> And you want to select one and leave it as the default.
> The simplest solution that comes to mind is
> {{{ DATABASES['default'] = DATABASES['sqlite1'] }}} .
>
> And now there is a funny piece of code
> {{{
> https://github.com/django/django/blob/master/django/db/backends/base/creation.py
> ...
> # Restore the original database name
> if old_database_name is not None:
> settings.DATABASES[self.connection.alias]["NAME"] =
> old_database_name
> self.connection.settings_dict["NAME"] = old_database_name
> }}}
>
> Suppose we run a test.
> In case of in-memory sqlite testing the "url" of in-memory database
> (something like {{{ file:memorydb_sqlite?mode=memory&cache=shared }}}
> gets replaced with the real sqlite db file path by the code above.
> Guess what happens in the second iteration?
> Real sqlite db is destroyed.
>
> May be this one is well known and every developer is aware of that?
> But still it is to easy to step into this trap in my opinion.
>
> I guess it should be documented somewhere or the code above somehow
> amended.
> (I don't know Django well enough to say whether that restoring old name
> is necessary or not)
New description:
I don't know if it is a bug or just a nasty feature, that appears to be
undocumented, or a well known caveat that I don't know about.
With a few seemingly innocent steps you can get your working sqlite
database destroyed during tests.
Suppose you hold a few database configs in settings.DATABASES:
{{{
DATABASES = { 'sqlite1': { ... }, 'sqlite2': { ... } }
}}}
And you want to select one and leave it as the default.
The simplest solution that comes to mind is
{{{ DATABASES['default'] = DATABASES['sqlite1'] }}} .
And now there is a funny piece of code, which is a part of the teardown
procedure:
{{{
https://github.com/django/django/blob/master/django/db/backends/base/creation.py
...
# Restore the original database name
if old_database_name is not None:
settings.DATABASES[self.connection.alias]["NAME"] =
old_database_name
self.connection.settings_dict["NAME"] = old_database_name
}}}
Suppose we run a test.
In case of in-memory sqlite testing the "url" of in-memory database
(something like {{{ file:memorydb_sqlite?mode=memory&cache=shared }}} gets
replaced with the real sqlite db file path by the code above.
The teardown procedure is repeated for every database config we have.
Guess what happens in the second iteration?
Real sqlite db is destroyed.
May be this one is well known and every developer is aware of that?
But still it is to easy to step into this trap in my opinion.
I guess it should be documented somewhere or the code above somehow
amended.
(I don't know Django well enough to say whether that restoring old name is
necessary or not)
--
--
Ticket URL: <https://code.djangoproject.com/ticket/29225#comment:1>
Django <https://code.djangoproject.com/>
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