Background job operator does not work when invoking a script block variable #9703
Description
When a variable with a script block is passed to a background job via using, the variable inside the job is a string instead of a script block.
As @bpayette indicated below, this was by design to reduce the risk of accidentally executing code; however, this clearly seems like a design flaw now that we have the & background operator in PowerShell, and while it can be worked around, any code that works around it should be unnecessary. It is worth mentioning that the workaround demonstrated below would continue to work even if this bug was fixed because objects of type scriptblock convert implicitly to string, so the likelihood of this causing an issue for folks if it was fixed should be very low.
Steps to reproduce
Invoke-Pester -ScriptBlock {
Describe 'Tests for using variables of specific types' -Tags 'CI' {
It 'Implicit using with background job operator and variable of type ScriptBlock' {
$sb = {Get-Process -Id $pid}
$job = & $sb &
$results = $job | Receive-Job -Wait
$results | Should -BeOfType PSObject
$results.PSTypeNames | Should -Contain Deserialized.System.Diagnostics.Process
}
}
}Expected behavior
Tests Passed: 1, Failed: 0, Skipped: 0, Pending: 0, Inconclusive: 0
Actual behavior
Tests Passed: 0, Failed: 1, Skipped: 0, Pending: 0, Inconclusive: 0
Workaround
Invoke-Pester -ScriptBlock {
Describe 'Tests for using variables of specific types' -Tags 'CI' {
It 'Implicit using with background job operator and variable of type ScriptBlock' {
$sb = {Get-Process -Id $pid}
$job = & ([scriptblock]::Create($sb)) &
$results = $job | Receive-Job -Wait
$results | Should -BeOfType PSObject
$results.PSTypeNames | Should -Contain Deserialized.System.Diagnostics.Process
}
}
}Environment data
Name Value
---- -----
PSVersion 6.2.0
PSEdition Core
GitCommitId 6.2.0
OS Microsoft Windows 10.0.17763
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0