Example of #PSDSC using #Pester for validating configuration data

ConfigDataPester.ps1

$ConfigurationData = @{
    AllNodes = @(
        @{
            NodeName = 'sql-01'
            Roles = @{
                Computer = @{
                    MachineName = 'sql-01'
                    DomainName  = 'example.com'
                    Credential  = 'Svc-Domain-Join@example.com'
                }
            }
        }
    )
    Credentials = @{
        'Svc-Domain-Join@example.com' = (Join-Path -Path $PSScriptRoot -ChildPath 'ConfigDataPester.clixml')
    }
}

# Mimic special variables in PSDSC configurations
$AllNodes = $ConfigurationData.AllNodes

Describe 'Structural Tests' {
    It 'Defines credential files' {
        $ConfigurationData.Keys -icontains 'Credentials' | Should Be $true
    }
    foreach ($CredName in $ConfigurationData.Credentials.Keys) {
        It "Defines existing credential file for $CredName" {
            Test-Path -Path $ConfigurationData.Credentials.$CredName | Should Be $true
        }
    }
}

# Mimic special variable $Node in enumeration
foreach ($Node in $ConfigurationData.AllNodes) {
    Describe "Node $($Node.NodeName)" {
        Context 'Role computer' {
            It 'Contains computer role' {
                $Node.Roles.Keys -icontains 'Computer' | Should Be $true
            }
            It 'Resolves credential object if specified' {
                if ($Node.Roles.Computer.Keys -icontains 'Credential') {
                    $ConfigurationData.Credentials.Keys -icontains $Node.Roles.Computer.Credential | Should Be $true
                }
            }
            It 'Specifies credentials for domain join' {
                $Node.Roles.Computer.Keys -icontains 'DomainName' | Should Be $true
                $Node.Roles.Computer.Keys -icontains 'Credential' | Should Be $true
            }
        }
    }
}