Only import engine driver modules as necessary

[juledwar]

Currently, the Postgres modules are always imported regardless of whether PG is being used. Fix this so that it's conditionally imported as required.

[ShubhamNagure]

i'd like to work on it.

[juledwar]

Awesome! Do you need any help to get going? Feel free to submit a PR and we can go from there.

[ShubhamNagure]

could you please explain to me what is it and what needed to be done?

best regards,
Shubham

[juledwar]

Sure.

See the code here: https://github.com/juledwar/db-testtools/blob/master/dbtesttools/fixtures.py#L109-L118

It's iterating over all the modules under dbtesttools.engines, looking for a class that has the same name as the TEST_ENGINE_FIXTURE environment variable.

To inspect that name, it first has to import the module, and in doing so imports all the Postgres module dependencies, like psycopg.

What we need instead is an index of the available drivers in a separate module (engines/__init__.py would work well) that will map these fixture names into the name of the module that contains them. For example:

fixture_map = {
    'PostgresContainerFixture': 'postgres',
    'SqliteMemoryFixture': 'sqlite',
}

Then the pick_engine_fixture could look up the matching entry from fixture_map and only import the necessary module.

Hopefully that makes sense?