纠缠忽略模拟

Question

考虑到我的powershell代码(不是函数中的，因为最后几个部分是正在运行的脚本，但是我想使用pester)检查我的脚本的一些内容，我的powershell代码WinVersion.ps1

$WindowsVersion = Get-CimInstance -ClassName Win32_Operatingsystem | select -expand Caption

我的Pester剧本：

BeforeAll {
    . $PSCommandPath.Replace('.Tests.ps1', '.ps1')
}

Describe "Test Server 2012" {
    It "Given Server 2012, return correct data" {
        Mock -CommandName Get-CimInstance -ParameterFilter {$ClassName -eq "Win32_Operatingsystem"} -MockWith {
            Write-Host "CIM"
            return [Microsoft.Management.Infrastructure.CimInstanc]@{
                Caption = "Microsoft Windows Server 2012 Datacenter"
            }
        }
        write-host $WindowsVersion
    }
}

我的写主机(在我的困扰脚本中)应该返回Microsoft Windows Server 2012 Datacenter，但是它会返回我自己的windows版本。因此它忽略了我的嘲弄。

我也尝试过没有ParameterFilter的模拟，但这也不起作用。

这就是Pester给我的结果：

Starting discovery in 1 files.
Discovery found 2 tests in 82ms.
Running tests.
[-] Test Server 2012.Given Server 2012, return correct data 46ms (45ms|1ms)
 Expected strings to be the same, but they were different.
 Expected length: 40
 Actual length:   31
 Strings differ at index 18.
 Expected: 'Microsoft Windows Server 2012 Datacenter'
 But was:  'Microsoft Windows 11 Enterprise'
            ------------------^
 at $WindowsVersion | Should -Be "Microsoft Windows Server 2012 Datacenter"

有什么线索吗？

Answer 1

有几件事：

1. ，正在测试的脚本在定义Mock之前正在运行，所以Get不会被模仿。
2. [Microsoft.Management.Infrastructure.CimInstanc]@{ Caption = "Microsoft Windows Server 2012 Datacenter"}实际上在计算机上工作吗？如果您将其复制并粘贴到PowerShell中，您会得到该对象的实例吗？您只需使用pscustomobject在它的位置[pscustomobject]@{Caption = "Microsoft Windows Server 2012 Datacenter"}

。

我可以想出两种方法来解决这个问题。

快速修复是将您的脚本点移到

Describe 'Test Server 2012' {
    BeforeAll {
        Mock -CommandName Get-CimInstance -ParameterFilter { $ClassName -eq 'Win32_Operatingsystem' } -MockWith {
            [pscustomobject]@{Caption = 'Microsoft Windows Server 2012 Datacenter' }
        }

        # source the script here after mock is defined but before tests are run 
        . $PSScriptRoot\somescript.ps1
    }

    It 'Given Server 2012, return correct data' {
        $WindowsVersion | Should -Be 'Microsoft Windows Server 2012 Datacenter'
    }
}

更好的解决办法可能是重新考虑如何进行测试。在脚本中定义函数可以更容易地进行测试。

BeforeAll {
    # Everything in this block executes before the tests are set up and ran

    # This command dot sources the script we are testing
    # . $PSCommandPath.Replace('.Tests.ps1', '.ps1')

    # Defining functions that can be run in our tests.  
    # This could instead be defined in the script that we are testing

    function Test-Mock {
        Get-CimInstance -ClassName Win32_Operatingsystem | Select-Object -ExpandProperty Caption
    }

    function Test-UnaffectedByMock{
        Get-CimInstance -ClassName Win32_Volume | Select-Object -ExpandProperty Caption
    }
}

Describe 'Test Server 2012' {
    BeforeAll {
        Mock -CommandName Get-CimInstance -ParameterFilter { $ClassName -eq 'Win32_Operatingsystem' } -MockWith {
            [pscustomobject]@{Caption = 'Microsoft Windows Server 2012 Datacenter' }
        }
    }

    It 'Given Server 2012, return correct data' {
        Test-Mock | Should -Be 'Microsoft Windows Server 2012 Datacenter'
    }

    It 'Supplying different ClassName should not run mock' {
        Test-UnaffectedByMock | Should -Not -Be 'Microsoft Windows Server 2012 Datacenter'
    }
}