When testing commands that work with the filesystem, Pester provides TestDrive. TestDrive is a temporary folder created in the current user's temporary directory.

The folder is created when Describe runs, and is destroyed afterwards.

Using TestDrive simplifies the setup process for the Remove-StaleFile function; for example, BeforeAll might become the following:

BeforeAll { 
    $extensions = '.txt', '.log', '.doc' 
    Push-Location 'TestDrive:' 
} 

AfterAll becomes the following:

AfterAll { 
    Pop-Location 
} 

In the event that a command cannot work with the TestDrive label, as is the case with .NET types and methods, as well as non-PowerShell commands, the full path can be discovered by using Get-Item. This can be executed anywhere inside of a Describe block:

(Get-Item 'TestDrive:').FullName