powershell-standards

name	powershell-standards
description	PowerShell coding standards with severity-tiered rules. Use when writing, reviewing, or generating PowerShell code.

PowerShell Standards

ERROR (mandatory)

• Use Set-StrictMode -Version Latest in scripts
• Use [CmdletBinding()] on all functions — enables -Verbose, -Debug, -ErrorAction
• Validate parameters with [ValidateNotNullOrEmpty()], [ValidateSet()], [ValidateRange()]
• Never use Invoke-Expression with user input
• Use -ErrorAction Stop with try/catch for error handling — not $ErrorActionPreference alone
• Never store credentials in scripts — use Get-Credential, SecretManagement, or environment variables

WARNING (recommended)

• Use approved verbs from Get-Verb for function names
• Use PascalCase for function names, camelCase for local variables
• Use full cmdlet names — no aliases in scripts (Get-ChildItem not gci)
• Use [OutputType()] attribute on functions
• Maximum function length: 60 lines (excluding parameter block and help)
• Use splatting for cmdlets with 3+ parameters
• Use Write-Verbose/Write-Debug over Write-Host for operational messages

RECOMMENDATION (optional)

• Use PSScriptAnalyzer for static analysis
• Use classes for complex domain objects (PowerShell 5.0+)
• Use ForEach-Object -Parallel for parallel processing (PowerShell 7+)
• Use $PSDefaultParameterValues for session defaults
• Consider Pester v5 for test infrastructure

Testing

• Use Pester 5+ with Describe/Context/It blocks
• Use Should -Invoke for mock verification
• Use TestDrive: for file system tests
• Mock external cmdlets — never hit real systems in unit tests