Crash when using PassthroughEnv

[drhagen]

Starting in v0.8.2, using @nox_poetry.session(venv_backend='none') causes a crash. This was introduced in #298 and is caused by accessing the nonexistant location attribute of the PassthroughEnv object in _PoetrySession.export_requirements.

Example script:

import nox_poetry

@nox_poetry.session(venv_backend='none')
def lint(session: nox_poetry.Session):
    session.install('flakehell', 'flake8', 'pep8-naming', 'flake8-quotes')
    session.run('flakehell', 'lint', 'src', 'tests', 'examples')

Example error message:

nox > Running session lint
nox > Session lint raised exception AttributeError("'PassthroughEnv' object has no attribute 'location'")
Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.9.4/x64/lib/python3.9/site-packages/nox/sessions.py", line 549, in execute
    self.func(session)
  File "/opt/hostedtoolcache/Python/3.9.4/x64/lib/python3.9/site-packages/nox/_decorators.py", line 53, in __call__
    return self.func(*args, **kwargs)
  File "/opt/hostedtoolcache/Python/3.9.4/x64/lib/python3.9/site-packages/nox_poetry/sessions.py", line 42, in wrapper
    function(proxy, *_args, **_kwargs)
  File "/home/runner/work/parsita/parsita/noxfile.py", line 22, in lint
    session.install('flakehell', 'flake8', 'pep8-naming', 'flake8-quotes')
  File "/opt/hostedtoolcache/Python/3.9.4/x64/lib/python3.9/site-packages/nox_poetry/sessions.py", line 276, in install
    return self.poetry.install(*args, **kwargs)
  File "/opt/hostedtoolcache/Python/3.9.4/x64/lib/python3.9/site-packages/nox_poetry/sessions.py", line 144, in install
    requirements = self.export_requirements()
  File "/opt/hostedtoolcache/Python/3.9.4/x64/lib/python3.9/site-packages/nox_poetry/sessions.py", line 200, in export_requirements
    tmpdir = Path(self.session.virtualenv.location) / "tmp"
AttributeError: 'PassthroughEnv' object has no attribute 'location'

[cjolowicz]

Thank you for catching this!

The idea in #298 was to, essentially, do what session.create_tmp does but without setting TMPDIR. Instead of session._runner.envdir we're using session.virtualenv.location because it's a public API. It was an oversight that this does not work for PassthroughEnv.

The fix would be here:

nox-poetry/src/nox_poetry/sessions.py

Lines 200 to 201 in 1afc0a0

	tmpdir = Path(self.session.virtualenv.location) / "tmp"
	tmpdir.mkdir(exist_ok=True)

I'd be fine with switching to the private API, and passing parents=True to ensure the directory can be created. This would be emulating session.create_tmp.

There have also been thoughts about using just a single requirements file for all sessions. I think we don't need per-session requirements files anymore. Edit: Opened #350 for this.

[cjolowicz]

Fix released in 0.8.5, could you give it a spin?

[drhagen]

I have confirmed that this is fixed.

[cjolowicz]

Thank you!