PR Summary

Implementation for PowerShell/PowerShell-RFC#391. For the PS team members, here is the internal PR for the equivalent change in CMD: https://microsoft.visualstudio.com/OS/_git/os.2020/pullrequest/10131240

A few implementation decisions:

1. Check the package manager list only once per process (same as CMD). So, changing the package manager list in registry doesn't affect a PowerShell session that is already running.

2. When detecting user/system PATH value changes, only check new items PREPENDED or APPENDED to the original string (same as CMD). The detection is made simple, which is not intended to detect complex changes to the user/system PATH.

3. The PATH update feature is disabled when the Environment provider is not available. The Environment provider is checked only once per PowerShell session (s_environmentProviderEnabled is thread static).

TODO

No test is added yet. Need help to brainstorm the best way to add test automation.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge. If this PR is a work in progress, please open this as a Draft Pull Request and mark it as Ready to Review when it is ready to merge.
• Breaking changes
  • None
  • OR
  • Experimental feature(s) needed
    • Experimental feature name(s):
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    • Issue filed:
• Testing - New and feature
  • N/A or can only be tested interactively
  • OR
  • Make sure you've added a new test if existing tests do not effectively test the code changed