private/Tests/Test-InstallMDT.ps1

function Test-InstallMDT {
    <#
    .SYNOPSIS
        Returns $true when Microsoft Deployment Toolkit is installed.
 
    .NOTES
        Author: David Segura
        Company: Recast Software
        Detection: Uninstall registry — DisplayName like
        'Microsoft Deployment Toolkit*'.
    #>

    [OutputType([bool])]
    param ()

    $regPaths = @(
        'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*',
        'HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*'
    )

    foreach ($regPath in $regPaths) {
        $entry = Get-ItemProperty -Path $regPath -ErrorAction SilentlyContinue |
            Where-Object { $_.PSObject.Properties['DisplayName'] -and $_.DisplayName -like 'Microsoft Deployment Toolkit*' } |
            Select-Object -First 1
        if ($entry) { return $true }
    }

    return $false
}