Set of 'package manager' like functions to help setup a powershell testing env

0_Powershell-Testing-Utils.ps1

# This module defines helper functions to help with local/CI testing PowerShell code,
# like checking pwsh version, installing up necessary modules..

function Assert-PowerShellVersion {
    param(
        [Parameter(Mandatory)]
        [string]$MinimumVersion
    )
    if ($PSVersionTable.PSVersion -le [System.Version]$MinimumVersion) {
        throw "PowerShell minimum version $MinimumVersion is required, current version is: $($PSVersionTable.PSVersion)"
    }
}

function Check-VersionAgainstConstraints {
    param(
        [Parameter(Mandatory, Position = 0)]
        [System.Version]$givenVersion,
        [Parameter(Mandatory, Position = 1)]
        [hashtable]$VersionConstraints
    )
    Set-StrictMode -Off # Disabled locally, to ease check for missing properties
    [System.Version]$min = $VersionConstraints.MinimumVersion ?? "0.0.0"
    [System.Version]$max = $VersionConstraints.MaximumVersion # allow $null
    if (!$max) {
        $min -le $givenVersion
    }
    else {
        $min -le $givenVersion -and $givenVersion -le $max
    }
}

function Ensure-AllModulesAvailable {
    param(
        [Parameter(Mandatory, Position = 0)]
        [hashtable]$modulesToCheck
    )
    foreach ($moduleName in $modulesToCheck.Keys) {
        # Wrap the loop body with a re-throwing try-catch, to ensure an error in the loop is
        # correctly propagated and stops the script.
        # (In PowerShell7 (@2024-01), a cmd failing with an error in a loop will just print the
        # error and ignore it, continuing as normal :/)
        try {
            Ensure-ModuleAvailable $moduleName -VersionConstraints $modulesToCheck[$moduleName]
        }
        catch {
            throw $_
        }
    }
}

function Ensure-ModuleAvailable {
    param(
        [Parameter(Mandatory, Position = 0)]
        [string]$Name,
        [Parameter(Mandatory, HelpMessage = "Version constraints with fields like `MinimumVersion`, `MaximumVersion`. Must be compatible to being passed to 'Install-Module' & 'Import-Module'")]
        [hashtable]$VersionConstraints
    )
    # Check the module is installed, and the version constraints are respected
    Write-Host "Checking module '$Name'"
    # NOTE: since there is no way to easily check that a package following version constraints is installed
    #   we have to get all versions of a given package and check the versions ourselves..
    $module = (
        Get-Module -Name $Name -ListAvailable
        | Where-Object { Check-VersionAgainstConstraints $_.Version $VersionConstraints }
        | Select-Object -Last 1
    )
    if ($module) {
        Write-Host "  👍 Module '$Name' is already installed"
    }
    else {
        Write-Host "  ❌ Module '$Name' is not installed or not at correct version"
        Write-Host "  👉 Installing module '$Name' with version constraints: $($VersionConstraints | ConvertTo-Json -Compress -Depth 10)"
        Install-Module -Name $Name -Force -Scope CurrentUser -SkipPublisherCheck @VersionConstraints
    }
}

Example-usage.ps1

Set-StrictMode -Version 3.0; $ErrorActionPreference = "Stop" # Ensure sane behavior

Import-Module $PSScriptRoot\..\..\powershell-modules\Pwsh-Testing-Utils.ps1 -force

# Require PowerShell 7 (version 5 is OLD!)
Assert-PowerShellVersion -MinimumVersion "7.0.0"

# Ensure required modules are installed for tests
Ensure-AllModulesAvailable @{
    "Pester" = @{ MinimumVersion = "5.2.0" }
    "Az"     = @{ MinimumVersion = "11.2.0" }
}