Pester provides a framework for running BDD style Tests to execute and validate PowerShell commands inside of PowerShell and offers a powerful set of Mocking Functions that allow tests to mimic and mock the functionality of any command inside of a piece of PowerShell code being tested. Pester tests can execute any command or script that is accessible to a pester test file. This can include functions, Cmdlets, Modules and scripts. Pester can be run in ad hoc style in a console or it can be integrated into the Build scripts of a Continuous Integration system.