困扰 5：自动化

Question

为了我的爱好项目ConvertTo-Expression, I am rebuilding my test (Pester 5) script. I would like to automate the It (and possibly the Context part) as there are large number of syntax formats to test for and the function actually roundtrips which &([ScriptBlock]::Create("$Expression")). For a Minimal, Reproducible Example, I am using ConvertTo-Json which roundtrips with ConvertTo-Json。
我对这个问题的目标基本上是创建一个 easy 测试语法相关函数是否正确往返，例如：

`Test -Compress '{"a":1}'`

我想做这样的事情：

Function Test ([String]$Json, [Switch]$Compress, [String]$It = $Json) {
    $Context = if ($Compress) { 'Compress' } Else { 'Default' }
    $Object = ConvertFrom-Json $Json
    Context $Context {
#       BeforeEach {
#           $Compress = $True
#           $Json = '{"a":1}'
#           $Object = ConvertFrom-Json $Json
#       }
        It $It { ConvertTo-Json -Compress:$Compress -Depth 9 $Object | Should -Be $Json }
    }
}

Describe 'Syntax check' {

    Test -Compress '{"a":1}'

}

但这会导致如下错误：

Starting discovery in 1 files.
Discovery finished in 35ms.
[-] Syntax check.Compress.{"a":1} 15ms (13ms|2ms)
 RuntimeException: The variable '$Compress' cannot be retrieved because it has not been set.
 at <ScriptBlock>, C:\Test.ps1:6
Tests completed in 140ms
Tests Passed: 0, Failed: 1, Skipped: 0 NotRun: 0

启用注释掉的硬编码 BeforeEach returns expcted 结果：

Starting discovery in 1 files.
Discovery finished in 32ms.
[+] C:\Test.ps1 197ms (80ms|88ms)
Tests completed in 202ms
Tests Passed: 1, Failed: 0, Skipped: 0 NotRun: 0

我想把It（和Context）放在一个函数中并用参数控制它们，这样我就可以做一个像Test -Compress '{"a":1}'这样的简单测试。不幸的是，我完全迷失在新的 Pester 发现范围中，并开始怀疑这是否真的可以通过 Pester 5 实现。

Answer 1

我找到了一种使用 -TestCases 参数的方法：

Function Test ([String]$Json, [Switch]$Compress, [String]$It = $Json) {
    $Context = if ($Compress) { 'Compress' } Else { 'Default' }
    $Object = ConvertFrom-Json $Json
    Context $Context {
        $TestCase = @{ Params = @{ Compress = $Compress; Object = $Object; Json = $Json } }
        It $It -TestCases $TestCase { 
            param($Params)
            ConvertTo-Json -Compress:$Params.Compress -Depth 9 $Params.Object | Should -Be $Params.Json
        }
    }
}

Describe 'Syntax check' {

    Test -Compress '{"a":1}'

}

（但我仍然愿意接受其他建议，尤其是如果我似乎忽略了一些明显的东西）

Answer 2

我认为问题在于感兴趣的变量仅在嵌套脚本块（传递给 It 的脚本块）内被引用，而不是外部（一个传递给 Context).

一个简单的解决方案是在外部脚本块上调用 .GetNewClosure() 方法，它在调用作用域的局部变量周围形成一个闭包：

Function Test ([String]$Json, [Switch]$Compress, [String]$It = $Json) {
    $Context = if ($Compress) { 'Compress' } Else { 'Default' }
    $Object = ConvertFrom-Json $Json
    Context $Context {
        It $It { ConvertTo-Json -Compress:$Compress -Depth 9 $Object | Should -Be $Json }
    }.GetNewClosure() # This captures $Json, $Compress, $It, and $Object
}

Describe 'Syntax check' {
    Test -Compress '{"a":1}'
}

请注意，docs are very terse at the moment, but the conversation in GitHub issue #9077 表明 .GetNewClosure() 返回的脚本块在新创建的 动态（内存中）模块中运行 。

困扰 5：自动化

Pester 5: Automate It

powershell

pester

`Test -Compress '{"a":1}'`