The PowerShell Pester module can be used to build unit tests for scripts and functions. Unit tests target the smallest possible unit of code, which, in PowerShell, is likely to be a function or a method in a PowerShell class.
Pester tests are saved in a file name ending with .tests.ps1 and executed using the Invoke-Pester command. Invoke-Pester finds files named *.tests.ps1 under a given path and executes all of the tests in each.
Describe and Should statements may also be entered in the console when exploring syntax, but this is not the normal method of defining and running tests.
While Pester is included with Windows 10, it is not the latest version. The latest version may be installed from PSGallery, as follows:
Install-Module Pester -Force
