fix(env): treat empty VIRTUAL_ENV/CONDA_PREFIX as unset#10784
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radoering merged 5 commits intopython-poetry:mainfrom Mar 28, 2026
Merged
fix(env): treat empty VIRTUAL_ENV/CONDA_PREFIX as unset#10784radoering merged 5 commits intopython-poetry:mainfrom
radoering merged 5 commits intopython-poetry:mainfrom
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Reviewer's GuideThis PR makes environment detection more robust by treating empty VIRTUAL_ENV and CONDA_PREFIX values as unset, updating env-prefix checks to use truthiness semantics, and adding tests to verify that Poetry falls back to the in-project .venv in these scenarios. Class diagram for updated environment and Python managersclassDiagram
class EnvManager {
+activate(python: str) Env
+get(reload: bool) Env
-create: bool
-env_prefix: str
-consecutive_calls: int
}
class PythonManager {
+find_all() Iterator~Python~
}
class VirtualEnv {
+VirtualEnv(path: Path)
}
class Python {
+executable: Path
}
EnvManager --> VirtualEnv : creates
PythonManager --> Python : returns
%% Highlighted behaviors related to this PR
class EnvManager {
-_detect_in_venv(env_prefix: str | None, conda_env_name: str | None) bool
}
class PythonManager {
-_current_venv_path: Path | None
}
Flow diagram for updated env detection in EnvManager.getflowchart TD
A["Start get(reload)"] --> B["Read env_prefix from environment"]
B --> C["Read conda_env_name from CONDA_DEFAULT_ENV"]
C --> D{"bool(env_prefix) and conda_env_name != base"}
D -- "False" --> E["Treat as not in_venv"]
E --> F{"Existing env instance and not reload"}
F -- "True" --> G["Return existing env"]
F -- "False" --> H{"Project .venv exists"}
H -- "True" --> I["Return VirtualEnv for project .venv"]
H -- "False" --> J["Create new project .venv"] --> I
D -- "True" --> K{"env_prefix is truthy"}
K -- "True" --> L["prefix = Path(env_prefix)"]
K -- "False" --> M["prefix = in-project .venv path"]
L --> N["Return VirtualEnv for prefix"]
M --> N
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Documentation Updates 1 document(s) were updated by changes in this PR: CHANGELOGView Changes@@ -1,4 +1,11 @@
# Change Log
+
+## [Unreleased]
+
+### Fixed
+
+- Fixed handling of empty `VIRTUAL_ENV` and `CONDA_PREFIX` environment variables. Poetry now treats empty environment variables the same as unset variables. This fixes issues where `conda deactivate` could leave `CONDA_PREFIX` set to an empty string, causing `poetry env use` and other commands to fail. ([#10784](https://github.com/python-poetry/poetry/pull/10784))
+
## [2.3.2] - 2026-02-01
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Hey - I've found 1 issue, and left some high level feedback:
- In
test_get_ignores_empty_env_prefix, consider using pytest’smonkeypatch.setenv/delenv(or a dedicated helper) instead of mutatingos.environdirectly with manualtry/finally, which will make the env setup/teardown more concise and less error-prone.
Prompt for AI Agents
Please address the comments from this code review:
## Overall Comments
- In `test_get_ignores_empty_env_prefix`, consider using pytest’s `monkeypatch.setenv/delenv` (or a dedicated helper) instead of mutating `os.environ` directly with manual `try/finally`, which will make the env setup/teardown more concise and less error-prone.
## Individual Comments
### Comment 1
<location path="tests/utils/env/test_env_manager.py" line_range="584-591" />
<code_context>
+ "env_var",
+ ["VIRTUAL_ENV", "CONDA_PREFIX"],
+)
+def test_get_ignores_empty_env_prefix(
+ manager: EnvManager,
+ poetry: Poetry,
+ in_project_venv_dir: Path,
+ env_var: str,
+ mocker: MockerFixture,
+) -> None:
+ """An empty VIRTUAL_ENV or CONDA_PREFIX should be treated as unset.
+
+ After ``conda deactivate``, conda can leave CONDA_PREFIX set to an
</code_context>
<issue_to_address>
**suggestion (testing):** Missing tests for empty VIRTUAL_ENV behavior in env_manager.activate and python.manager.find_all
This test covers `EnvManager.get()` for empty `VIRTUAL_ENV`/`CONDA_PREFIX`, but the other updated code paths still lack coverage:
1. `EnvManager.activate` now uses `bool(os.environ.get("VIRTUAL_ENV"))` and should be tested with `VIRTUAL_ENV=""` to confirm it behaves as if no venv is active.
2. `python.manager.PythonManager.find_all` (or equivalent) should be tested with `VIRTUAL_ENV=""` to ensure it does not treat the empty string as a valid venv path.
Adding these tests would round out coverage for all call sites affected by the bugfix.
Suggested implementation:
```python
@pytest.mark.parametrize(
"env_var",
["VIRTUAL_ENV", "CONDA_PREFIX"],
)
def test_get_ignores_empty_env_prefix(
manager: EnvManager,
poetry: Poetry,
in_project_venv_dir: Path,
env_var: str,
mocker: MockerFixture,
) -> None:
"""An empty VIRTUAL_ENV or CONDA_PREFIX should be treated as unset.
After ``conda deactivate``, conda can leave CONDA_PREFIX set to an
empty string. Poetry should not consider that as an active
virtualenv and should fall back to the in-project .venv instead.
See: https://github.com/python-poetry/poetry/issues/10770
"""
os.environ.pop("VIRTUAL_ENV", None)
os.environ.pop("CONDA_PREFIX", None)
os.environ[env_var] = ""
virtualenv_init = mocker.patch(
"poetry.utils.env.virtual_env.VirtualEnv.__init__",
return_value=None,
)
env = manager.get(poetry)
# EnvManager.get() should ignore the empty env var and use the in-project venv.
assert env.path == in_project_venv_dir
virtualenv_init.assert_called_once_with(in_project_venv_dir, in_project_venv_dir)
# EnvManager.activate() should also treat an empty VIRTUAL_ENV as "no active venv".
# When VIRTUAL_ENV is empty, this should behave the same as when it is unset.
activate_env = manager.activate(poetry)
assert activate_env.path == in_project_venv_dir
# The activation path should also rely on the in-project venv, not the empty env var.
# We re-use the same VirtualEnv.__init__ patch to ensure no extra call with an empty
# path sneaks through in the activate code path.
assert virtualenv_init.call_count >= 1
def test_python_manager_find_all_ignores_empty_virtual_env(
poetry: Poetry,
in_project_venv_dir: Path,
mocker: MockerFixture,
) -> None:
"""PythonManager.find_all should ignore an empty VIRTUAL_ENV.
This mirrors the EnvManager behavior: VIRTUAL_ENV="" must not be treated
as a valid virtual environment path.
"""
from poetry.utils.env import EnvManager
from poetry.utils.env.python_manager import PythonManager
os.environ.pop("VIRTUAL_ENV", None)
os.environ["VIRTUAL_ENV"] = ""
manager = EnvManager(poetry)
python_manager = PythonManager(poetry)
# Patch whatever path discovery the PythonManager uses so we can assert it
# does not attempt to inspect the empty VIRTUAL_ENV path.
list_venvs = mocker.patch.object(
python_manager,
"list",
return_value=[in_project_venv_dir],
)
envs = python_manager.find_all(manager)
# The empty VIRTUAL_ENV should not be treated as a candidate environment.
assert in_project_venv_dir in envs
list_venvs.assert_called_once_with()
```
The SEARCH block is based on the visible portion of `test_get_ignores_empty_env_prefix`; you may need to adjust it to match the exact function body in your local copy.
The new `test_python_manager_find_all_ignores_empty_virtual_env` assumes:
1. `PythonManager` lives in `poetry.utils.env.python_manager`.
2. `PythonManager` has a `list()` method that returns discovered virtualenv paths.
3. `PythonManager.find_all(manager)` is the public API you want to exercise.
If the actual API differs (e.g., different module path or method names), you should:
- Update the imports accordingly.
- Patch the appropriate method used internally by `find_all` to look up venv locations.
- Adjust the assertions on the patched method to match how your real implementation works.
</issue_to_address>Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.
After `conda deactivate`, conda can leave `CONDA_PREFIX` set to an empty string. Poetry was treating this as an active virtualenv because it only checked `is not None` rather than truthiness. This caused `poetry env use` and other commands to fail with an empty prefix path. Change all env-prefix checks to use truthiness (`bool(...)` / `if env_prefix:`) so that an empty string is treated the same as an unset variable. Fixes python-poetry#10770
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Co-authored-by: Randy Döring <30527984+radoering@users.noreply.github.com> (cherry picked from commit 0206165)
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Summary
conda deactivate, conda can leaveCONDA_PREFIXset to an empty string. Poetry previously only checkedis not None, treating the empty string as an active virtualenv, causingpoetry env useand other commands to fail.bool(...)/if env_prefix:) so an empty string is treated the same as an unset variable.VIRTUAL_ENVchecks inenv_manager.py(line 162) andpython/manager.pyfor consistency and defensive correctness.VIRTUAL_ENVandCONDA_PREFIXempty-string scenarios.Fixes #10770
Test plan
test_get_ignores_empty_env_prefixparametrized overVIRTUAL_ENVandCONDA_PREFIXmanager.get()falls back to the in-project.venvwhen the env variable is set to an empty stringSummary by Sourcery
Handle empty virtual environment prefix variables as unset across environment detection and Python discovery.
Bug Fixes:
Enhancements:
Tests: