Find-EmptyDirs.psm1

function Find-EmptyDirs {
    param(
        [parameter(Mandatory = $true, Position = 0)]
        [ValidateScript({ Test-Path $_ })]
        [string] $Path,
        [parameter(Mandatory = $false, Position = 1)]
        [switch] $Hidden,
        [parameter(Mandatory = $false, Position = 2)]
        [array] $Exclude
    )
    $Path = $Path.TrimEnd('\')
    $empty = @{}
    Get-ChildItem @PSBoundParameters -Recurse -Directory | %{$empty[$_.FullName] = $true}

    Get-ChildItem @PSBoundParameters -Recurse -File -Exclude "desktop.ini" | ForEach-Object {
        for($d = $_.Directory; $d.FullName -ine $Path; $d = $d.Parent) {
            if($empty[$d.FullName] -eq $false) { break }
            $empty[$d.FullName] = $false
        }
    }
    return $empty.Keys | Where-Object { $empty[$_] }
}

# Create test folder structure
function Make-Tree {
    param($tmpdir,$count=1000)

    $dirs = New-Object System.Collections.ArrayList($count+1)
    $dirs.Add($tmpdir) | Out-Null

    1..$count | %{
        $dir = $dirs[(Get-Random -Maximum $dirs.count -Minimum 0)]
        $path = Join-Path -path $dir -childpath (Get-Random -Maximum 99999999 -Minimum 1000000).ToString()
        mkdir -path $path | Out-Null
        $dirs.Add($path) | Out-Null
    }

    1..$count | %{
        $dir = $dirs[(Get-Random -Maximum $dirs.count -Minimum 0)]
        $filename = "$((Get-Random -Maximum 99999999 -Minimum 1000000).ToString()).dat"
        $file = Join-Path -path $dir -childpath $filename
        Set-Content -Path $file -Value ""
    }
}

# Check that a test is true or output the test
function assert {
    param($test)
    if($test -eq $true) { return }
    $stack = Get-PSCallStack
    $line = ($stack[0].InvocationInfo.Line -replace 'assert','').Trim()
    $num = ($stack[0].ScriptLineNumber)
    throw "Assertion failed $line at line $num"
}

# Test Find-EmptyDirs
function Test-EmptyDirs {
    param(
        [parameter(Mandatory=$true,Position=0)] $tmpdir
    )

    if ((dir $tmpdir).count -gt 0) {
        throw "$tmpdir is not empty. Please specify an empty path."
    }

    #fix tmpdir case
    $tmpdir = (Get-Item $tmpdir).FullName

    # Make some test files
    mkdir "$tmpdir\empty" | Out-Null
    mkdir "$tmpdir\empty\sub"| Out-Null
    mkdir "$tmpdir\full"| Out-Null
    mkdir "$tmpdir\fullsub"| Out-Null
    mkdir "$tmpdir\fullsub\sub"| Out-Null
    sc -Path "$tmpdir\full\file.txt" -Value ""
    sc -Path "$tmpdir\fullsub\sub\file.txt" -Value ""
    
    $res = Find-EmptyDirs -Path $tmpdir
    assert $res.Contains("$tmpdir\empty")
    assert $res.Contains("$tmpdir\empty\sub")
    assert !$res.Contains("$tmpdir\full")
    assert !$res.Contains("$tmpdir\fullsub")
    assert !$res.Contains("$tmpdir\fullsub\sub")
    assert !$res.Contains("$tmpdir\full\file.txt")
    assert !$res.Contains("$tmpdir\fullsub\sub\file.txt")
    
    # Do random tests
    1..100 | %{
        Make-Tree $tmpdir -count 100
        $dirs = Find-EmptyDirs -Path $tmpdir
        $failed = $dirs | ?{ (Get-ChildItem -Path $_ -Recurse -File).count -gt 0 }
        assert ($failed.count -le 0)
        del -Path "$tmpdir\*" -Force -Recurse
        Write-Host "Completed $_ iterations"
    }
}