fix(dsc): make PSResourceList test, set and what-if agree on desired state

[Gijs Reijn (Gijsreyn)]

PR Summary

test, set and what-if for psresourcelist each computed desired state on their own and disagreed. They now share one pairing step (GetPSResourceListActions) that matches every desired resource to its current resource by index and decides None, Install or Uninstall.

PR Context

This PR fixes the following points:

1. test only checked the first resource.

   # PSScriptAnalyzer is installed, Pester is not
   repositoryName: PSGallery
   resources:
     - name: PSScriptAnalyzer
     - name: Pester

   # before: dsc resource test
   _inDesiredState: true
   differingProperties: []
   
   # after
   _inDesiredState: false
   differingProperties: [resources]
   

2. A resource without version never converged.

   repositoryName: PSGallery
   resources:
     - name: Pester

   # before: dsc resource set
   {"error":"Failed to install resource 'Pester' with version ''. Error: Cannot validate argument on parameter 'Version'. The argument is null or empty."}
   exit code 4
   
   # after
   Install-PSResource -Name Pester -Repository PSGallery      # -Version is left out, latest is installed
   exit code 0
   

3. set compared every desired resource against every current one.

   # test_local_mod 1.0.0 and 2.0.0 are installed
   repositoryName: LocalRepo
   resources:
     - name: test_local_mod
       version: 1.0.0
     - name: test_local_mod
       version: 2.0.0
       _exist: false

   # before: 1.0.0 was also matched against the second entry and removed
   Uninstall-PSResource -Name test_local_mod -Version 1.0.0
   Uninstall-PSResource -Name test_local_mod -Version 2.0.0
   
   # after: each desired entry is paired with its own current resource
   Uninstall-PSResource -Name test_local_mod -Version 2.0.0
   

4. All resources were installed or uninstalled with the last resource's scope.

   repositoryName: PSGallery
   resources:
     - name: PSScriptAnalyzer
       scope: CurrentUser
     - name: Pester
       scope: AllUsers

   # before
   Install-PSResource -Name PSScriptAnalyzer -Scope AllUsers
   Install-PSResource -Name Pester           -Scope AllUsers
   
   # after
   Install-PSResource -Name PSScriptAnalyzer -Scope CurrentUser
   Install-PSResource -Name Pester           -Scope AllUsers
   

5. _exist is compared before version and repository, and those only apply when specified.

   # Pester is not installed
   repositoryName: PSGallery
   resources:
     - name: Pester
       _exist: false

   # before: empty version '' compared against '' failed, so the resource was never in desired state
   _inDesiredState: false
   
   # after
   _inDesiredState: true
   

6. Uninstall removes the resource from the scope it is installed in.

   Before, Uninstall-PSResource received the desired scope, which defaults to CurrentUser when omitted. A resource installed in AllUsers was therefore never removed and set never converged.

   # Pester is installed in AllUsers
   repositoryName: PSGallery
   resources:
     - name: Pester
       _exist: false

   # before: nothing to remove in CurrentUser, Pester stays installed, exit code 0
   Uninstall-PSResource -Name Pester -Scope CurrentUser
   
   # after
   Uninstall-PSResource -Name Pester -Scope AllUsers
   

Note

scope is still not a filter. GetPSResourceList matches the current resource on name and version across both scopes, so an explicit scope: CurrentUser with _exist: false also removes an AllUsers copy. I'll create another issue for it.

7. Errors trace at error level, so the real message is visible without --trace-level debug.

   # before: dsc resource set (default trace level)
   ERROR Installation failed
   
   # after
   {"error":"Failed to install resource 'Pester' with version '99.0.0'. Error: Package 'Pester' with version '99.0.0' could not be found in repository 'PSGallery'."}
   ERROR Installation failed
   

This PR also includes a couple of behavioral changes:

• _exist: false with a version removes only that version (range); without version all versions are removed.
• What-if reports a scope mismatch as Would install, matching what set does.
• Error text is shown by default.

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 and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: or [ WIP ] to the beginning of the title (the WIP bot will keep its status check at Pending while the prefix is present) and remove the prefix when the PR is ready.
• Breaking changes
  • None
  • OR
  • Documentation needed
    • Issue filed:
• 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
• Tooling
  • I have considered the user experience from a tooling perspective and don't believe tooling will be impacted.
  • OR
  • I have considered the user experience from a tooling perspective and enumerated concerns in the summary.

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[Copilot]

Copilot review overview

🟡 Changes recommended

Unresolved issues affect scope-aware convergence, install deduplication, and test isolation.

Get a fresh assessment by requesting another Copilot review.

Review effort: Lite
Findings: 2

Open (2)

• Prefer resources matching the desired scope · New
• Include resource scope in install deduplication key · New

What changed in this PR

Unifies PSResourceList desired-state evaluation across test, set, and what-if.

Changes:

• Centralizes resource action pairing.
• Handles versions, scopes, _exist, and error tracing.
• Adds DSC regression coverage.

File	Description
test/​DscResource/​PSResourceGetDSCResource.Tests.ps1	Adds regression and scope-related tests.
src/​dsc/​psresourceget.ps1	Implements shared desired-state actions and scope-aware operations.

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