No WhatIf output in Foreach-Object -Parallel

[tleepa]

When I run a command with -WhatIf switch within a Foreach-Object loop, it shows the "What if: ..." output.
When doing the same with -Parallel, this output is not shown.

If there is Write-Host statement in loop body, it is visible in both cases.

Is there anything I can do about it? Is it a bug, or by design?

Steps to reproduce

Prepare some directories:

("test1", "test2", "test3") | ForEach-Object { New-Item -Path .\$_ }

Then remove them with -WhatIf switch using -Parallel

("test1", "test2", "test3") | ForEach-Object -Parallel { Remove-Item -Path .\$_ -WhatIf }

Expected behavior

Should be the same as running:

("test1", "test2", "test3") | ForEach-Object { Remove-Item -Path .\$_ -WhatIf }

What if: Performing the operation "Remove File" on target "<current dir>\test1".
What if: Performing the operation "Remove File" on target "<current dir>\test2".
What if: Performing the operation "Remove File" on target "<current dir>\test3".

Actual behavior

<No ouput>

Environment data

❯ $PSVersionTable

Name                           Value
----                           -----
PSVersion                      7.1.2
PSEdition                      Core
GitCommitId                    7.1.2
OS                             Microsoft Windows 10.0.19041
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

[TravisEz13]

Remoting working group: We still need to figure out why this is not coming through and possibly add a feature.

Do you have a real-life scenario that you need to run whatif in parallel?

[tleepa]

Well, I am using parallel to loop over actions in Azure, that can be time-consuming.
I am using a -Noop switch in my scripts and run some commands using -WhatIf:$Noop. This way I don't have to test for the switch value and run different commands.
But it is not a deal breaker :)

[TravisEz13]

❯ Copy-Item ./test.ps1 ./test2.ps1 -WhatIf *> test.txt
What if: Performing the operation "Copy File" on target "Item: /Users/******/git/powershell/test.ps1 Destination: /Users/********/git/powershell/test2.ps1".

I did a little investigation. It appears that -whatif writes directly to the host and is not redirectable.

I'll let @PaulHigin speak for what this means for foreach-object -parallel but I don't think it is good.

[JustinGrote]

@TravisEz13 this would be solved by: #9870

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has been marked as "No Activity" as there has been no activity for 6 months. It has been closed for housekeeping purposes.