How to Mock PowerShell Cmdlets in Pester

Variable Names for ParameterFilter in Cmdlets

• Write-Debug: $Message
• Write-Error: $Message
• Write-Host: $Object
• Write-Information: $MessageData
• Write-Output: $InputObject
• Write-Verbose: $Message
• Write-Warning: $Message

Mocking with Pester: This page provides detailed documentation on how to use Pester for mocking in PowerShell, including examples and best practices.

function DoSomething() {
    # some code to execute and test
    Write-Debug "My Message"
}

Describe "DoSomething" {
    Context "Given that ..." {
        It "Write a debug message" {
            # Arrange
            # Mock the Write-Debug cmdlet to verify its invocation
            Mock Write-Debug
            # Act
            DoSomething
            # Assert
            Should -Invoke -CommandName Write-Debug -Exactly 1 -Scope It -ParameterFilter { $Message -eq "My Message" }
        }
    }
}