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Ensure -PipelineVariable is set for all output from script cmdlets #12766

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Merged
rjmholt merged 2 commits into from
Dec 10, 2020
Merged

Ensure -PipelineVariable is set for all output from script cmdlets #12766

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bbbb4ee
:bug: Fix PipelineVariable not being set correctly
vexx32 May 22, 2020
7b0a58b
:white_check_mark: Add test for pipelinevariable
vexx32 May 23, 2020
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11 changes: 11 additions & 0 deletions src/System.Management.Automation/engine/MshCommandRuntime.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3744,6 +3744,17 @@ internal void SetVariableListsInPipe()

if (this.PipelineVariable != null)
{
// _state can be null if the current script block is dynamicparam, etc.
if (_state != null)
{
// Create the pipeline variable
_state.PSVariable.Set(_pipelineVarReference);

// Get the reference again in case we re-used one from the
// same scope.
_pipelineVarReference = _state.PSVariable.Get(this.PipelineVariable);
}

this.OutputPipe.SetPipelineVariable(_pipelineVarReference);
}
}
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56 changes: 56 additions & 0 deletions test/powershell/engine/ParameterBinding/ParameterBinding.Tests.ps1
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Expand Up @@ -256,6 +256,62 @@ Describe "Parameter Binding Tests" -Tags "CI" {
DynamicParamTest -PipelineVariable bar | ForEach-Object { $bar } | Should -Be "hi"
}

Context "PipelineVariable Behaviour" {

BeforeAll {
function Write-PipelineVariable {
[CmdletBinding()]
[OutputType([int])]
param(
[Parameter(ValueFromPipeline)]
$a
)
begin { 1 }
process { 2 }
end { 3 }
}

$testScripts = @(
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@JamesWTruher JamesWTruher Jun 3, 2020

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i'm a little concerned that there isn't enough validation. Can you think of additional edges here that we should be poking?

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@vexx32 vexx32 Jun 3, 2020 •
edited
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There are probably numerous odd cases where this might crop up, but I can't think of any that are really different from the test case here. At the very least, this does cover the test case that we know is currently broken.

I've not seen any other cases crop up myself, nor had someone drop in the community channels with an issue that came down to this. I suspect that that's more due to -PipelineVariable being a bit more of a niche concept from the start, though.

Without knowing for sure about other broken cases, the best I can do is test a few other cases with multiple script cmdlets and various mixes of script / compiled cmdlets to see if the logic breaks down anywhere.

The only real unknown where I don't know what to actually expect is what is meant to happen if multiple cmdlets in the same pipeline declare the same pipeline variable. I'm not sure the expected behaviour there is even recorded anywhere. Best guess - the nearest command to the variable's usage will have its output in there at any given point...

If anyone else has cases they know to be broken / likely to break, I'd appreciate having those as well.

@{
CmdletType = 'Script Cmdlet'
Script = {
1..3 |
Write-PipelineVariable -PipelineVariable pipe |
Select-Object -Property @(
@{ Name = "PipelineVariableSet"; Expression = { $null -ne $pipe ? $true : $false } }
@{ Name = "PipelineVariable"; Expression = { $pipe } }
)
}
}
@{
CmdletType = 'Compiled Cmdlet'
Script = {
1..3 |
Write-PipelineVariable |
ForEach-Object { $_ } -PipelineVariable pipe |
Select-Object -Property @(
@{ Name = "PipelineVariableSet"; Expression = { $null -ne $pipe ? $true : $false } }
@{ Name = "PipelineVariable"; Expression = { $pipe } }
)
}
}
)
}

AfterAll {
Remove-Item -Path 'function:Write-PipelineVariable'
}

It 'should set the pipeline variable every time for a <CmdletType>' -TestCases $testScripts {
param($Script, $CmdletType)

$result = & $Script
$result.Count | Should -Be 5
$result.PipelineVariableSet | Should -Not -Contain $false
$result.PipelineVariable | Should -Be 1, 2, 2, 2, 3
}
}

Context "Use automatic variables as default value for parameters" {
BeforeAll {
## Explicit use of 'CmdletBinding' make it a script cmdlet
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