[英]Null List in Pester Mock created from a closure
為什么執行以下代碼:
function CreateExecutedCommandsLogger(){
param(
[System.Collections.Generic.List[System.String]]$cmdLog
)
"WWWWW=>{0}" -f $cmdLog | Write-Host
return{
param(
[parameter(valuefrompipeline)]$command
)
"XXXXX=>{0}" -f $command | Write-Host
"YYYYY=>{0}" -f $cmdLog | Write-Host
$cmdLog.Add($command)
}.GetNewClosure()
}
$executedCommands = New-Object System.Collections.Generic.List[System.String]
Mock ExecuteSqlCommand (CreateExecutedCommandsLogger $executedCommands)
導致錯誤:
RuntimeException: You cannot call a method on a null-valued expression.
at <ScriptBlock>, <No file>: line 7
at <ScriptBlock>, C:\Users\notme\Documents\WindowsPowerShell\Modules\Pester\Functions\Mock.ps1: line 1018
at ExecuteBlock, C:\Users\notme\Documents\WindowsPowerShell\Modules\Pester\Functions\Mock.ps1: line 1022
at Invoke-Mock, C:\Users\notme\Documents\WindowsPowerShell\Modules\Pester\Functions\Mock.ps1: line 868
at <ScriptBlock><Process>, <No file>: line 53
供參考,跟蹤輸出給出:
WWWWW=>System.Collections.Generic.List`1[System.String]
XXXXX=>C:\dummy\command.exe -S "blah" -d "blahblah" -i "something.sql"
YYYYY=>
當我使用以下內容時,它可以工作:
$dummyMock = (CreateExecutedCommandsLogger $executedCommands)
&$dummyMock "blah"
我假設這與模擬中的腳本塊的執行方式有關?
從源代碼(Get-Command Mock).ScriptBlock
可以看到,在一行中使用$MockWith
參數:
$mockWithCopy = [scriptblock]::Create($MockWith.ToString())
因此, $MockWith
實際上是一個字符串,任何閉包都將被忽略。 之所以可能這樣做是因為在下一行中,新創建的腳本塊$mockWithCopy
綁定到某個會話狀態,因此無論如何您都會松開閉包:
Set-ScriptBlockScope -ScriptBlock $mockWithCopy -SessionState $contextInfo.Session
Pester首先執行腳本塊的私有副本,以不影響傳遞的實例。
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