test: add system_python_nodeps_test

[rickeylev]

Adds a simple system_python bootstrap test. Such a test otherwise doesn't directly
exist, and only ends up accidentally tested by something in an example directory.

[gemini-code-assist]

Summary of Changes

Hello @rickeylev, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request primarily focuses on enhancing the robustness and testability of Python rules, with a significant emphasis on improving Windows compatibility and debugging capabilities. It introduces a new test to verify system Python behavior without dependencies, alongside several fixes and enhancements to PowerShell scripts and Python bootstrap templates. These changes address Windows-specific challenges related to file paths, encoding, and permissions, while also adding verbose logging to facilitate the diagnosis of bootstrap-related issues.

Highlights

• New Test Added: Introduced a new system_python_nodeps_test to validate the behavior of system Python bootstraps without additional dependencies.
• Windows Compatibility Enhancements: Improved Windows compatibility for build data writing by refactoring the PowerShell script to use .NET for file operations, ensuring UTF-8 encoding without Byte Order Mark (BOM), and setting appropriate file permissions. Additionally, Windows-specific path handling and BOM support were added to the Python stage2 bootstrap template.
• Improved Debugging and Diagnostics: Added verbose logging for key bootstrap variables and paths within the Python bootstrap template to aid in diagnosing issues. Error reporting for missing Python binaries and build data file access has also been enhanced with more context.
• Path Handling Refinement: Updated py_executable.bzl to utilize a dedicated runfiles_root_path function for generating stage2_bootstrap paths, promoting consistent and correct path resolution.
• Robust Test Cleanup: Modified wheel_installer_test.py to gracefully handle potential file deletion errors on Windows during test cleanup by ignoring errors when removing the temporary wheel directory.

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Changelog

• python/private/build_data_writer.ps1
  • Refactored file writing logic to use .NET's WriteAllLines for improved encoding control (UTF-8 without BOM) and to mitigate PowerShell's file locking issues.
  • Added logic to set file system access control lists (ACLs) to grant read access for 'Everyone' to the output file.
  • Updated conditional checks for VersionFilePath and InfoFilePath to include Test-Path.
• python/private/py_executable.bzl
  • Replaced manual string formatting for the stage2_bootstrap path with a call to the runfiles_root_path function.
• python/private/python_bootstrap_template.txt
  • Added verbose print statements for STAGE2_BOOTSTRAP, PYTHON_BINARY, PYTHON_BINARY_ACTUAL, IS_ZIPFILE, RECREATE_VENV_AT_RUNTIME, WORKSPACE_NAME, main_rel_path, and runfiles root.
  • Enhanced the error message when FindPythonBinary fails to include both PYTHON_BINARY and PYTHON_BINARY_ACTUAL for better debugging.
• python/private/stage2_bootstrap_template.py
  • Added a comment indicating that BUILD_DATA_FILE uses forward slashes and requires conversion for Windows.
  • Implemented Windows-specific path conversion for rlocation_path and path using replace("/", "\\") and os.path.normpath.
  • Opened BUILD_DATA_FILE with encoding='utf-8-sig' to correctly handle Windows Byte Order Mark (BOM).
  • Enhanced exception handling to add notes about the rlocation_path, file existence, and readability when get_build_data fails.
• tests/bootstrap_impls/BUILD.bazel
  • Loaded py_binary and py_test rules.
  • Added a new py_test target named system_python_nodeps_test configured to use the system_python bootstrap implementation.
• tests/bootstrap_impls/system_python_nodeps_test.py
  • Added a simple Python script that prints 'Hello, world'.
• tests/pypi/whl_installer/wheel_installer_test.py
  • Modified the tearDown method to use shutil.rmtree(..., ignore_errors=True) to prevent errors during directory deletion on Windows.

Activity

• The pull request is currently marked as 'DO NOT MERGE' and is awaiting changes from pull request chore: better bootstrap logging #3608.

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[gemini-code-assist]

Code Review

This pull request adds a new test, system_python_nodeps_test, and introduces several valuable improvements for Windows compatibility and debuggability. The changes to the PowerShell script build_data_writer.ps1 and the Python bootstrap templates are particularly beneficial, enhancing the robustness of file writing and path handling. The adoption of .NET APIs for file operations and the more detailed exception information are excellent additions. I have one minor suggestion to improve code consistency.