fix: Improve symlink check and sysconfig path handling #2914
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* Make `fs_supports_symlink` perform a real symlink creation check on all platforms * Add a test case for environments without symlink support and `--copies` flag * Handle missing keys in `sysconfig_path` to prevent `KeyError` Fixes pypa#2786
gaborbernat
approved these changes
Jul 31, 2025
gaborbernat
requested changes
Jul 31, 2025
auto-merge was automatically disabled
July 31, 2025 16:24
Pull request was converted to draft
This commit addresses two main issues:
1. A bug where creating a virtual environment on a filesystem without symlink support would fail because the check was not robust enough.
2. A confusing error message when no creation method (symlink or copy) is available.
Summary of changes:
- Modified `fs_supports_symlink` in `src/virtualenv/info.py` to perform a real symlink creation check on all platforms, not just Windows. This ensures that `virtualenv` correctly detects filesystems that do not support symlinks and can fall back to copies.
- Improved the error message in `src/virtualenv/create/via_global_ref/api.py` to be more informative when no creation method is available, showing the reason for each method's failure.
- Added two new tests to `tests/unit/create/test_creator.py`:
- `test_fallback_to_copies_if_symlink_unsupported`: Verifies that `virtualenv` successfully falls back to using copies when symlinks are not supported on a system that allows copying.
- `test_fail_gracefully_if_no_method_supported`: Verifies that `virtualenv` raises a detailed `RuntimeError` on systems where both symlinks and copies are disabled.
- Fixed an unrelated bug in `src/virtualenv/discovery/py_info.py` that caused a `KeyError: 'headers'` during test collection in environments without Python development headers.
- Fixed several linter issues.
The changes have been validated by running a focused set of tests, which all passed.
for more information, see https://pre-commit.ci
…g' into fix-symlink-check-and-headers-bug
* Mock `is_macos_brew` to return `False` to test the generic fallback case. * This allows testing the fallback to copies when symlinks are unsupported.
* Refine test for symlink fallback when copy is unsupported. * Ensure the `is_macos_brew` check is correctly applied. * Update the error message for brew-related copy failures. * Add a skip condition for brew python on macOS to avoid testing unsupported copy scenarios.
gaborbernat
approved these changes
Jul 31, 2025
This was referenced Aug 1, 2025
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fs_supports_symlinkperform a real symlink creation check on all platforms--copiesflagsysconfig_pathto preventKeyErrorFixes #2786
tox -e fix)docs/changelogfolder