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Fix unhelpful KeyError when using invalid VIRTUALENV_DISCOVERY value #3031

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Merged
gaborbernat merged 3 commits into from
Feb 15, 2026
Merged

Fix unhelpful KeyError when using invalid VIRTUALENV_DISCOVERY value #3031

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9547f3a
Fix unhelpful KeyError when using invalid VIRTUALENV_DISCOVERY value
veeceey Feb 13, 2026
9c20fce
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Feb 13, 2026
ad2face
Fix ruff PT011: add match parameter to pytest.raises
veeceey Feb 14, 2026
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7 changes: 7 additions & 0 deletions src/virtualenv/run/plugin/discovery.py
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,13 @@ def get_discover(parser, args):
help="interpreter discovery method",
)
options, _ = parser.parse_known_args(args)

# Check if the specified discovery method is valid
if options.discovery not in discover_types:
available = ", ".join(f"'{key}'" for key in sorted(discover_types.keys()))
msg = f"Invalid discovery method '{options.discovery}'. Available options: {available}"
raise ValueError(msg)

discover_class = discover_types[options.discovery]
discover_class.add_parser_arguments(discovery_parser)
options, _ = parser.parse_known_args(args, namespace=options)
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12 changes: 12 additions & 0 deletions tests/unit/test_run.py
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Original file line number Diff line number Diff line change
Expand Up @@ -41,3 +41,15 @@ def test_logging_setup(caplog, on):
assert not caplog.records
else:
assert caplog.records


def test_invalid_discovery_method_via_env(monkeypatch):
"""Test that an invalid discovery method via env var raises a helpful error."""
monkeypatch.setenv("VIRTUALENV_DISCOVERY", "pyenv")
with pytest.raises(ValueError, match=r"Invalid discovery method 'pyenv'") as exc_info:
session_via_cli(["env"])

error_message = str(exc_info.value)
assert "Invalid discovery method 'pyenv'" in error_message
assert "Available options:" in error_message
assert "'builtin'" in error_message
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