MAAS cloud model name issue when initializing ops_test fixture

[dashmage]

While running tests on a MAAS juju cloud where the model is named admin/mymodel according to the <user>/<model> convention, the ops_test fixture does not work.

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Steps to reproduce error

Models are named admin/mymodel and admin/controller.

Have a simple test that calls the ops_test fixture.

def test_something(ops_test):
    assert True

And run pytest path/to/test.py --model admin/mymodel to execute the tests.

Analysis

I was trying to reuse my existing model by providing --model admin/mymodel but this still tried to create a new model (and promptly failed since I wasn't the admin user on the cloud). Upon tracing the execution flow from the plugin.py -> ops_test -> _setup_model -> track_model -> _model_exists where the last method is used to set the value of the use_existing variable which was getting the wrong value (should be True, getting False).

This seemed to be due to the fact that the self._controller.list_models() returns the models but without prefixing the user name (without "admin" in this instance).

async def _model_exists(self, model_name: str) -> bool:
    """
    returns True when the model_name exists in the model.
    """
    all_models = await self._controller.list_models()
    return model_name in all_models

# all_models had the value ['controller', 'mymodel'] but model_name is "admin/mymodel"

As seen above, the _model_exists method returns False when the self._controller.list_models() returns the wrong name for the current model.

Temporary workaround

Made changes here.

return model_name.split("/")[-1] in all_models