PowerShell CI pipeline using VSTS and Pester

Article
12/19/2016

I talked about BDD on PowerShell meetup Tokyo. I'd like to share some tips for enabling BDD and Continuous Integration using VSTS.

If you create a decent Unit tests when you write a PowerShell, you can feel safe and sound. Also if you have continuous integration system for your PowerShell, You can notice the problem of your PowerShell.

Let's get started.

I use Pester for BDD framework for PowerShell.

You can clone my GitHub repository for setting up your environment.

https://github.com/TsuyoshiUshio/PowerShellCISampl

Setting up Pester module

SetupPester.ps1 enable us to setup Pester module. You need to copy Pester files to the UserModulePath.

 function Get-UserModulePath {
 
 $Path = $env:PSModulePath -split ";" -match $env:USERNAME
 
 if (-not (Test-Path -Path $Path))
 {
 New-Item -Path $Path -ItemType Container | Out-Null
 }
 $Path
}
$path = Get-UserModulePath
Write-Output $path 
Copy-Item -Path Pester -Destination $path -Recurse
Import-Module Pester
Get-Module -Name Pester | Select -ExpandProperty ExportedCommands | Write-Output

Then import Paster Module. See UnitTest.ps1

 Unblock-File -Path "..\..\Pester-master.zip"
Import-Module Pester
Invoke-Pester -OutputFile TEST-RESULT.xml -OutputFormat "LegacyNUnitXml"

2. Unit Testing

This command Generate a PowerShell and an UnitTest.

 PS1 > New-Fixture -Path HelloWorldExample -Name Get-HelloWorld

HelloWorld.ps1

 function Get-HelloWorld {
 
}

HelloWorld.Test.ps1

 $here = Split-Path -Parent $MyInvocation.MyCommand.Path
$sut = (Split-Path -Leaf $MyInvocation.MyCommand.Path) -replace '\.Tests\.', '.'
. "$here\$sut"

Describe "Get-HelloWorld" {
 It "outputs 'Hello World!" {
 Get-HelloWorld | Should Be 'Hello World!'
 }
}

Invoke-Pester command invokes your powershell unit testing. This is an example of failure of an unit test.

 PS1 > Invoke-Pester

Describing Get-HelloWorld
 [-] outputs 'Hello World! 152ms
 Expected: {Hello World!}
 But was: {}
 7: Get-HelloWorld | Should Be 'Hello World!'
 at <ScriptBlock>, C:\Users\tsushi\Codes\PowerShell\Pester\HelloWorldExample\HelloWorldExample\Get-HelloWorld.Tests.ps1: line
 7