Class-based PowerShell DSC Resources include hidden properties in `dsc config` results

Prerequisites

[X] Write a descriptive title.
[X] Make sure you are able to repro it on the latest version
[X] Search the existing issues.

Steps to reproduce

Create the files for a new PowerShell module

mkdir ./dsc-repro/psdsc.repro
touch ./dsc-repro/psdsc.repro/psdsc.repro.psd1
touch ./dsc-repro/psdsc.repro/psdsc.repro.psm1

Define the module manifest:

@{
   RootModule           = 'psdsc.repro.psm1'
   ModuleVersion        = '0.0.1'
   GUID                 = '361fff1b-423a-423f-9e05-39f5ab94a437'
   Author               = 'Bug Reproducer'
   CompanyName          = 'Unknown'
   Copyright            = '(c) Bug Reproducer. All rights reserved.'
   FunctionsToExport    = '*'
   CmdletsToExport      = '*'
   VariablesToExport    = '*'
   AliasesToExport      = '*'
   DscResourcesToExport = @(
       'ReproResultData'
   )
   PrivateData          = @{ PSData = @{} }
}

Define the root module script:

[DscResource()] class ReproResultData {
           [DscProperty(Key)]             [string] $KeyProperty
           [DscProperty()]                [string] $NormalProperty
                                          [string] $NonDscProperty
   hidden                                 [string] $HiddenNonDscProperty
   hidden  [DscProperty()]                [string] $HiddenDscProperty
   static  [DscProperty(NotConfigurable)] [string] $StaticDscProperty = @(
       'This property could be in results data,'
       'but is an anti-pattern unless the property'
       'is read-only.'
   ) -join ' '
   static                                 [string] $StaticNonDscProperty = @(
       "This property shouldn't be in results data,"
       "because it's not a DSC property."
   ) -join ' '

   ReproResultData() {
       $this.NormalProperty = 'Should be in results data.'
       $this.NonDscProperty = @(
           "This property shouldn't be in results data,"
           "because it's not a DSC property."
       ) -join ' '
       $this.HiddenNonDscProperty = @(
           "This property shouldn't be in results data,"
           "because it's hidden and not a DSC property."
       ) -join ' '
       $this.HiddenDscProperty = @(
           'This property should be in results data,'
           'but is an anti-pattern.'
       ) -join ' '
   }

   [ReproResultData] Get() {
       $Current             = [ReproResultData]::new()
       $Current.KeyProperty = $this.KeyProperty

       return $Current
   }

   [bool] Test() { return $true }
   [void] Set()  { }
}

Add the folder containing the repro module to the PSModulePath:

$env:PSModulePath += [System.IO.Path]::PathSeparator + "$PWD/dsc-repro"

Confirm you can get the ReproResultData dsc resource and see its properties:

$Resource = Get-DscResource -Module psdsc.repro

ImplementationDetail : ClassBased
ResourceType         : ReproResultData
Name                 : ReproResultData
FriendlyName         :
Module               : psdsc.repro
ModuleName           : psdsc.repro
Version              : 0.0.1
Path                 : C:\code\dsc-repro\psdsc.repro\psdsc.repro.psd1
ParentPath           : C:\code\dsc-repro\psdsc.repro
ImplementedAs        : PowerShell
CompanyName          : Unknown
Properties           : {KeyProperty, DependsOn, HiddenDscProperty, NormalProperty…}

$Resource | Select-Object -ExpandProperty Properties | Format-Table

Name                 PropertyType   IsMandatory Values
----                 ------------   ----------- ------
KeyProperty          [string]              True {}
DependsOn            [string[]]           False {}
HiddenDscProperty    [string]             False {}
NormalProperty       [string]             False {}
PsDscRunAsCredential [PSCredential]       False {}

dsc --format yaml resource list psdsc.repro/ReproResultData

# Formatted for easier reading
type          : psdsc.repro/ReproResultData
version       : 0.0.1
path          : C:\code\dsc-repro\psdsc.repro\psdsc.repro.psd1
description   : null
directory     : C:\code\dsc-repro\psdsc.repro
implementedAs : ClassBased
author        : ''
properties    : [
                   KeyProperty,
                   DependsOn,
                   HiddenDscProperty,
                   NormalProperty,
                   PsDscRunAsCredential
               ]
requires      : DSC/PowerShellGroup
manifest      : null

Invoke the resource with Invoke-DscResource

$PSInvokeParams = @{
   Method   = 'Get'
   Module   = 'psdsc.repro'
   Name     = 'ReproResultData'
   Property = @{ KeyProperty = 'Repro Example (PSDSC)' }
}
$PSInvokeResult = Invoke-DscResource @PSInvokeParams
$PSInvokeResult | Format-List

KeyProperty    : Repro Example (PSDSC)
NormalProperty : Should be in results data.
NonDscProperty : This property shouldn't be in results data, because it's not a DSC property.

Invoke the resource with dsc resource:

$V3InvokeResult = '{ "KeyProperty": "Repro Example (DSCv3)" }' |
   dsc resource get -r psdsc.repro/ReproResultData |
   ConvertFrom-Json |
   Select-Object -ExpandProperty actualState
$V3InvokeResult | Format-List

KeyProperty          : Repro Example (DSCv3)
NormalProperty       : Should be in results data.
NonDscProperty       : This property shouldn't be in results data, because it's not a DSC property.
HiddenNonDscProperty : This property shouldn't be in results data, because it's hidden and not a DSC property.
HiddenDscProperty    : This property should be in results data, but is an anti-pattern.

Compare the actual and preferred output statuses, with metadata:

filter Test-HasAttribute($Property, $Attribute) {
   [bool]($Property.CustomAttributes.AttributeType -eq $Attribute)
}
filter Test-InPropertySet($Property, $InputObject) {
   $Set = if ($InputObject -is [Microsoft.PowerShell.DesiredStateConfiguration.DscResourceInfo]) {
       $InputObject.Properties
   } else {
       $InputObject.psobject.Properties
   }
   $Property.Name -in $Set.Name
}
filter Test-IsHidden ($p) {
   $a = [System.Management.Automation.HiddenAttribute]
   Test-HasAttribute -Property $p -Attribute $a
}
filter Test-IsDscProperty ($p) {
   $a = [System.Management.Automation.DscPropertyAttribute]
   Test-HasAttribute -Property $p -Attribute $a
}
filter Test-ShouldBeInResult ($p) {
   $IsDscProperty    = Test-IsDscProperty $_
   $IsHiddenProperty = Test-IsHidden      $_

   $IsDscProperty -and (-not $IsHiddenProperty)
}
$PSInvokeResult.GetType().GetProperties() | Format-Table -Property @(
   'Name'
   @{ Name = 'InResourceInfo'    ; Expression = { Test-InPropertySet $_ $Resource }}
   @{ Name = 'InPSDscResult'     ; Expression = { Test-InPropertySet $_ $PSInvokeResult }}
   @{ Name = 'InV3DscResult'     ; Expression = { Test-InPropertySet $_ $V3InvokeResult }}
   @{ Name = 'ShouldBeInResults' ; Expression = { Test-ShouldBeInResult $_ }}
   @{ Name = 'IsDscProperty'     ; Expression = { Test-IsDscProperty $_ }}
   @{ Name = 'IsHidden'          ; Expression = { Test-IsHidden $_ }}
   @{ Name = 'IsStatic'          ; Expression = { $_.GetGetMethod().IsStatic }}
)

Name                 InResourceInfo InPSDscResult InV3DscResult ShouldBeInResults IsDscProperty IsHidden IsStatic
----                 -------------- ------------- ------------- ----------------- ------------- -------- --------
KeyProperty                    True          True          True             False          True    False    False
NormalProperty                 True          True          True             False          True    False    False
NonDscProperty                False          True          True             False         False    False    False
HiddenNonDscProperty          False         False          True             False         False     True    False
HiddenDscProperty              True         False          True             False          True     True    False
StaticDscProperty             False         False         False             False          True    False     True
StaticNonDscProperty          False         False         False             False         False    False     True

Expected behavior

$Invoking = @{
    Method   = 'Get'
    Module   = 'psdsc.repro'
    Name     = 'ReproResultData'
    Property = @{ KeyProperty = 'Repro Example' }
}
Invoke-DscResource @Invoking | Format-List

KeyProperty    : Repro Example
NormalProperty : Should be in results data.

$invoking.Property |
    ConvertTo-Json |
    dsc resource get -r "$($i.Module)/$($i.Name)" |
    ConvertFrom-Json |
    Select-Object -ExpandProperty actualState |
    Format-List

KeyProperty          : Repro Example
NormalProperty       : Should be in results data.

Actual behavior

$Invoking = @{
    Method   = 'Get'
    Module   = 'psdsc.repro'
    Name     = 'ReproResultData'
    Property = @{ KeyProperty = 'Repro Example' }
}
Invoke-DscResource @Invoking | Format-List

KeyProperty    : Repro Example
NormalProperty : Should be in results data.
NonDscProperty : This property shouldn't be in results data, because it's not a DSC property.

$invoking.Property |
    ConvertTo-Json |
    dsc resource get -r "$($i.Module)/$($i.Name)" |
    ConvertFrom-Json |
    Select-Object -ExpandProperty actualState |
    Format-List

KeyProperty          : Repro Example
NormalProperty       : Should be in results data.
NonDscProperty       : This property shouldn't be in results data, because it's not a DSC property.
HiddenNonDscProperty : This property shouldn't be in results data, because it's hidden and not a DSC property.
HiddenDscProperty    : This property should be in results data, but is an anti-pattern.

Error details

No response

Environment data

Name                           Value
----                           -----
PSVersion                      7.3.6
PSEdition                      Core
GitCommitId                    7.3.6
OS                             Microsoft Windows 10.0.22621
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Version

DSC (build from main), PSDSC v2.0.7

Visuals

No response

Notes

While both PSDSC and DSCv3 do show the NonDscProperty in the results, that seems like a bug in PSDesiredStateConfiguration. Similarly, the non-inclusion of StaticDscProperty is (arguably) a bug in PSDesiredStateConfiguration.

However, the return data handling by the DSC/PowerShellGroup resource provider is to just convert the result data to JSON:

https://github.com/PowerShell/DSC/blob/6b286f190c81f2652cfe1fbbbfe10474467eece5/powershellgroup/powershellgroup.resource.ps1#L179

This runs into PowerShell/PowerShell#9847, where the serialization unexpectedly includes hidden properties (compared to ConvertTo-Csv and Select-Object).

Fix Proposal

Filter the returned properties to only include properties with the DscProperty attribute, so that the schema surface for the resources matches with Get-DscResource and the contract that the class definition implements.

PowerShell / DSC