PowerShell Koans

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About the Author

Joel Sallow

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Synopsis

Inspired by Chris Marinos' fantastic F# koans, the goal of the PowerShell koans is to teach you PowerShell by presenting you with a set of questions. Each kōan (each question) is represented by a failing Pester test. Your goal is to make those tests pass by filling out the correct answer, or writing the correct code. The koans start very simple to get you familiar with the basic concepts and progress towards more difficult. Teaching you multiple beginner, intermediate and advanced aspects of PowerShell in the process.

To get started please navigate to prerequisites and getting started.

Command Reference

View the PSKoans Command Reference Documentation.

Prerequisites

• PowerShell version 5.1 / PowerShell 6+
• NuGet (Windows only)
• Pester v4.x

Windows only: If you've never installed PowerShell modules before, you need to first install the NuGet PackageProvider to enable modules to be installed:

Install-PackageProvider -Name NuGet -MinimumVersion 2.8.5.201 -Force

To install the latest version of Pester, use the appropriate command for your version of PowerShell:

# PS 5.1 (upgrade to latest Pester)
Install-Module Pester -Force -SkipPublisherCheck -Scope CurrentUser -MinimumVersion 5.0.2

# PS 6.0+ (Install Pester under current user)
Install-Module Pester -Scope CurrentUser -MinimumVersion 5.0.2

Getting Started

Install from Gallery

Install-Module PSKoans -Scope CurrentUser

Or Download the Repo

1. git clone the repository into your desired directory, or download the module zip file from the build artifacts available on this page.
2. From a normal powershell session run Get-ChildItem -Recurse | Unblock-File in that directory to remove the "downloaded from internet" flag that blocks them from running.
3. Check Get-ExecutionPolicy: if it says 'Restricted' or 'Undefined', you need to also run Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser in order to allow the scripts to run.
4. Add the repository folder to $env:PSModulePath so that PowerShell can see it.
   • From the repository main folder, run: $env:PSModulePath = "$(Get-Location)$([IO.Path]::PathSeparator)${env:PSModulePath}"

Start your Journey

1. Run Show-Karma to start your journey towards PowerShell enlightenment

You will be presented with a page describing your goal:

Inspect the red messages carefully, most importantly the last one. The error message contains path to the file that you need to edit in order to progress forward. In this case, you'll need to examine Introduction\AboutAssertions.Koans.ps1.

2. Run Show-Karma -Contemplate to open your Koans folder

Navigate to Introduction\AboutAssertions.Koans.ps1. Near the top you'll see:

It 'is a simple comparison' {
    # Some truths are absolute.
    $____ | Should -Be $true
}

The $___ represents a blank for you to fill, and | Should -Be $true shows the expected result. To pass this koan you need to replace $____ with $true to fulfil the assertion: $true | Should -Be $true

3. Run Show-Karma again to see how you did

You passed your first koan! You'll notice that your overall progress updated to 1/635 and you are presented with the next challenge.

You are on your own from here, but the progression should be fairly smooth. If you need help, you can always ask around in the PowerShell communities:

• Slack
• Discord
• Reddit
• Twitter
• PowerShell.org Forums

Good luck!

Backing Up Your Progress

You can see the current folder your copy of the koans is stored in by calling Get-PSKoanLocation. If you want to save a backup of your current progress, simply make a copy of this folder and store it in a safe location.

For example:

Get-PSKoanLocation | Copy-Item -Recurse -Destination "D:\Backups\PSKoans"

Maintaining Multiple Koan Libraries

Just as you can Get-PSKoanLocation, you can also use Set-PSKoanLocation to change the directory that PSKoans will look for. This allows you to have any number of in-progress libraries of koans on a single machine without moving any folders.

However, be aware that the module does not retain any information about previous locations specified, only the current location. To change the set location, call Set-PSKoanLocation with the path you would like to set. If the specified folder does not exist, it will be created the next time you call Show-Karma.

$oldLocation = Get-PSKoanLocation
Set-PSKoanLocation "~/New/PSKoans"

# Call Show-Karma to create the directory and populate it with a fresh koan library
Show-Karma

# Restore the old location
$newLocation = Get-PSKoanLocation
Set-PSKoanLocation $oldLocation

# Call Show-Karma again to check the progress on the old library once again
Show-Karma

Uninstallation

You can uninstall the PSKoans module the usual way you uninstall PowerShell modules, with Uninstall-Module -Name PSKoans This will not remove your copy of the koans themselves, which are stored in your user folder, and it will also not remove the configuration file.

To completely remove all of these files, call these commands before you uninstall PSKoans:

# To remove configuration settings
Remove-Item -Path "~/.config/PSKoans" -Recurse

# To remove your koan files (THIS WILL COMPLETELY DELETE YOUR PROGRESS)
Get-PSKoanLocation | Remove-Item -Recurse

Contributing

If you would like to contribute to PSKoans, please check out the Contributing document.

Support the Project

If you would like to support the project, you can:

• Sponsor me on Github
• Become a Patreon Patron
• Donate with Ko-fi