PowerShell ValidateSet

The Powershell validate set can be used to validate the powershell parameters that are getting supplied to the script. This is useful, when you want to validate a boolean value like True or False, or when you want to ensure that, user is selecting the right choice, when supplying the input values to a function or a script.

 
Function Sample-Validation {
    [cmdletbinding()]
    Param(
          [Parameter(Position=0,Mandatory=$True, HelpMessage="Select the choice, True or False")]
          [ValidateSet("True","False" )]
          [string]$Choice = "False",
          [ValidateNotNullorEmpty()]
         )
      $Choice
}
  
# Sample Choices
Sample-Validation -Choice "True"
Sample-Validation -Choice "False"
Sample-Validation -Choice "Falseeeee"
Sample-Validation -Choice $null
Sample-Validation -Choice ""

Similare write ups can be found in the Microsoft dev blogs here