PSShouldProcess behavior allows for unsafe code to pass where it should fail

Steps to reproduce

The following function will pass PSShouldProcess

function Test-Fail {
    [CmdletBinding(SupportsShouldProcess)]
    param ()
    process {
        Remove-Item -Path C:\temp\a_testy.txt -Force -Confirm:$false -ErrorAction SilentlyContinue
    }
}

@seeminglyscience pointesd me to this
https://github.com/PowerShell/PSScriptAnalyzer/blob/a7d23f7f4dbf4ee92077f5471e28ca334caef429/Rules/UseShouldProcessCorrectly.cs#L245-L267

Where it is checking upstream functions for supports should process. While on the surface it may seem like a good idea to allow the upstream functions to handle the confirmation, this allows for some unsafe code to pass where it should fail.

IMO, the best course would be to always warn when $PSCmdlet.ShouldProcess() is not present in the function itself and require suppression when allowing the upstream functions to handle the confirmation.

Expected behavior

Either a warning or the requirement to suppress PSShouldProcess

Actual behavior

Test passes

Environment data

> $PSVersionTable
Name                           Value
----                           -----
PSVersion                      5.1.16299.251
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.16299.251
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
> (Get-Module -ListAvailable PSScriptAnalyzer).Version | ForEach-Object { $_.ToString() }
1.16.0
1.15.0
1.13.0
1.12.0
1.8.1
1.16.1

Empieza por Rules/UseShouldProcessCorrectly.cs, especialmente por la comprobación de la función upstream alrededor de las líneas 245-267, y reproduce el problema con la función de PowerShell mostrada. Confirma que el analizador informa del comportamiento ausente de $PSCmdlet.ShouldProcess() o requiere una supresión, y después añade cobertura para la advertencia esperada o el requisito de supresión.