如何使用 PowerShell 多线程并通过 Pester Mocks 进行单元测试

Question

我正在尝试在 Powershell 中执行简单的并行操作。我正在使用 PoshRSJobs 进行多线程处理，尽管我也尝试过 Invoke-Parallel 解决同样的问题。我需要在作业的脚本主体中调用几个我自己的函数，但这不允许我模拟这些函数以进行单元测试（它们最终成为原始的非模拟函数）。在这一点上，我只是想断言他们被调用的次数正确。

这是原文class（导入模块的功能无关紧要 - 实际实现当前正在返回测试字符串）...

Import-Module $PSScriptRoot\Convert-DataTable
Import-Module $PSScriptRoot\Get-History
Import-Module $PSScriptRoot\Get-Assets
Import-Module $PSScriptRoot\Write-DataTable

function MyStuff (
    param(
        [string]$serverInstance = "localhost\SQLEXPRESS", 
        [string]$database = "PTLPowerShell",
        [string]$tableName = "Test"
    )
    $assets = Get-Assets
    $full_dt = New-Object System.Data.DataTable
    $assets | Start-RSJob -ModulesToImport $PSScriptRoot\Convert-FLToDataTable, $PSScriptRoot\Get-FLHistory {
        $history = Get-History $asset
        $history_dt = Convert-DataTable $history
        return $history_dt.Rows
    } | Wait-RSJob | Receive-RSJob | ForEach { 
        $full_dt.Rows.Add($_) 
    }
    Write-DataTable $serverInstance $database $tableName $full_dt
}

这是 Pester 测试...

$here = Split-Path -Parent $MyInvocation.MyCommand.Path
$sut = (Split-Path -Leaf $MyInvocation.MyCommand.Path) -replace '\.Tests\.', '.'
. "$here$sut"

Describe "MyStuff" {
    BeforeEach {
        Mock Get-Assets { return "page1", "page2"}
        Mock Get-History { return "history" }
        Mock Convert-DataTable { 
            $historyDT = New-Object System.Data.Datatable;
            $historyDT.TableName = 'Test'
            return ,$historyDT
        }
        Mock Write-DataTable {}
    }
    It "should do something" {
        { MyStuff } | Should -Not -Throw;
    }
    It "should call Get-FLAssetGrid" {
        Assert-MockCalled Get-Assets 1
    }
    It "should call Get-FLHistory" {
        Assert-MockCalled Get-History 2
    }
    It "should call Convert-DataTable" {
        Assert-MockCalled Convert-DataTable 2
    }
    It "should call Write-DataTable" {
        Assert-MockCalled Write-DataTable 1
    }
}

这是目前 Pester 测试的输出...

Describing MyStuff
  [+] should do something 1.71s
  [+] should call Get-Assets 211ms
  [-] should call Get-History 61ms
    Expected Get-History to be called at least 2 times but was called 0 times
    23:         Assert-MockCalled Get-History 2
    at <ScriptBlock>, myFile.Tests.ps1: line 23
  [-] should call Convert-DataTable 110ms
    Expected Convert-DataTable to be called at least 2 times but was called 0 times
    26:         Assert-MockCalled Convert-DataTable 2
    at <ScriptBlock>, myFile.Tests.ps1: line 26
  [+] should call Write-DataTable 91ms

所以最终，我正在寻找一种在 PowerShell 中执行并行操作并且仍然能够模拟和单元测试它们的方法。

Answer 1

我认为这不是一个完整的答案，我也没有从事 Pester 项目，但我想说这根本不是 Pester 支持的方案。这可能会改变 when/if concurrent programming becomes part of PowerShell proper（也可能不会）。

如果您愿意更改您的实现，您或许可以绕过此限制来支持某种测试。

例如，您的函数可能在只有 1 件事要做时不使用 RSJob（在测试时可能很方便）。

或者你可以实现一个 -Serial 或 -NoParallel 或 -SingleRunspace 开关（或者你在测试中设置为 1 的 -ConcurrencyFactor），其中对于这些情况，您不使用运行空间。

根据您的示例，很难判断这种测试是否充分测试了您想要的内容，但看起来确实如此。

Answer 2

我能够通过将模拟注入线程来让它工作；这是一个概念教授，但需要根据具体情况确定细节

#code.ps1
function ToTest{
   start-job -Name OG -ScriptBlock {return (Get-Date '1/1/2000').ToString()}
}

纠缠

#code.Tests.ps1
$DebugPreference = 'Continue'
write-debug 'Pester''ng: code.ps1'
#################################################################
. (join-path $PSScriptRoot 'code.ps1')
Describe 'Unit Tests' -Tag 'Unit' {
   Mock start-job {
      $NewSB = {
         &{describe 'MockingJob:$JobName' {
            Mock get-date {'got mocked'}

            & {$ScriptBlock} | Export-Clixml '$JobName.xml'
         }}
         $out = Import-Clixml '$JobName.xml'
         remove-item '$JobName.xml'
         $out | write-output
      }.ToString().Replace('$ScriptBlock',$ScriptBlock.ToString()).Replace('$JobName',$Name)
      start-job -Name "Mock_$Name" -ScriptBlock ([ScriptBlock]::Create($NewSB))
   } -ParameterFilter {$Name -NotMatch 'Mock'}

   It 'uses the mocked commandlet' {
      $job = ToTest
      receive-job -Job $job -wait | should be 'got mocked'
      remove-job  -Job $job
   }
}
$DebugPreference = 'SilentlyContinue'

如何使用 PowerShell 多线程并通过 Pester Mocks 进行单元测试

How to use PowerShell multithreading and still unit test with Pester Mocks

powershell

multithreading

mocking

pester