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# Adds BeforeAll at the top of Tests file to make it follow Pester v5 recommendation of putting
# all code into Pester controlled blocks.

# DO this:
#  BeforeAll {
#     . $PSScriptRoot/Code.ps1
# }

# DO this:
#  BeforeAll {

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# Quickly measuring if it is better to call function in foreach loop or gerate the array and pass it in the function once
# and then iterate over the array inside of the function
"`n"
# cross function boundary 10,000 times
$script:b = 0
function a ($a) { $script:b += $a }
$sw = [Diagnostics.StopWatch]::StartNew()
foreach ($_ in 1..10000) {
    a 1
}

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# output

Pester v4.9.0
Executing all tests in 'C:\Users\jajares\Dropbox\pester\parameters.tests.ps1'

Executing script C:\Users\jajares\Dropbox\pester\parameters.tests.ps1

  Describing a
    [+] b 31ms
    [+] c 15ms

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$callStack = Get-PSCallStack
$caller = $callStack[1].ScriptName
$callerDirectory = Split-Path $caller

[string] $PSGitRoot = $null
if ((Get-Command 'git' -ErrorAction Ignore))
{
    $workTree = @(git rev-parse --git-path $callerDirectory --is-inside-work-tree)
    if (0 -lt $workTree.Count -and 'true' -eq $workTree[-1]) {
        $PSGitRoot = Resolve-Path (@(git rev-parse --git-path $callerDirectory --show-toplevel)[-1])

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Describe "In Pester v5 assertions don't fail by default" {
    It "is awesome for ensuring a lot of stuff about single object" {
        $user = @{
            Name = 'Jakub'
            Age = 31
            Languages = [PSCustomObject]@{
                Speaking = 'Czech', 'English'
                Programming = @(
                    'C#'
                    'PowerShell'

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Get-Module m | Remove-Module
New-Module -Name m -ScriptBlock { 
    function Do-Expensive { }
} | Import-Module 

function f () {
    $variable = 2
    # if ($variable -eq 1) {
        Do-Expensive
    # }

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Get-Module Pester, m | Remove-Module
Import-Module Pester -MaximumVersion 4.9.9
New-Module -Name m -ScriptBlock { 
    function a { "hello" }
    function b { a }

    Export-ModuleMember -Function b
} | Import-Module

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# this snippet describes how to automatically clean up
# changes in environment varables
# it can clean up re-writing, adding and removing
# scroll down to see how to use it in real test

Get-Module Pester | Remove-Module 
Import-Module Pester -MaximumVersion 4.9.9
 
function Get-Environment {
    $vars = Get-Item Env:\ 

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Import-Module Pester -MaximumVersion 4.9.9

# use the fact that closures are dynamic modules with 
# their own session state, and that scriptblocks are bound
# to the session state that created them, that makes 
# the call to `dot` transparent, because the scope
# that the function creates is in a different sessionstate
# and so the `$ScriptBlock` still dot-sources directly into
# the calling session state, just like with the naked `.`
$function:dot = { 

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# Sets variable $a = 1000 in the local scope from which it was called from, like $matches in regex
Get-Module m | Remove-Module
New-Module m {
    function f {
        [CmdletBinding()]
        param()

        $sb = [ScriptBlock]::Create('param($Value);  $a = $Value')
        $ExecutionContext.InvokeCommand.InvokeScript($PSCmdlet.SessionState, $sb, @(1000))
    }