# Pester

**Repository Path**: mirrors_felixfbecker/Pester

## Basic Information

- **Project Name**: Pester
- **Description**: PowerShell BDD style testing framework
- **Primary Language**: Unknown
- **License**: Apache-2.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-09-24
- **Last Updated**: 2026-07-18

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Pester
> :fire: We recently released Pester 4 and there are breaking changes, please see [release notes](https://github.com/pester/Pester/releases/tag/4.0.7) and [migration guide](https://github.com/pester/Pester/wiki/Migrating-from-Pester-3-to-Pester-4).

Pester is the ubiquitous test and mock framework for PowerShell.

```powershell
# your function
function Get-Planet ([string]$Name='*')
{
  $planets = @(
    @{ Name = 'Mercury' }
    @{ Name = 'Venus'   }
    @{ Name = 'Earth'   }
    @{ Name = 'Mars'    }
    @{ Name = 'Jupiter' }
    @{ Name = 'Saturn'  }
    @{ Name = 'Uranus'  }
    @{ Name = 'Neptune' }
  ) | foreach { [PSCustomObject]$_ }

  $planets | where { $_.Name -like $Name }
}

# Pester tests
Describe 'Get-Planet' {
  It "Given no parameters, it lists all 8 planets" {
    $allPlanets = Get-Planet
    $allPlanets.Count | Should -Be 8
  }

  Context "Filtering by Name" {
    It "Given valid -Name '<Filter>', it returns '<Expected>'" -TestCases @(
      @{ Filter = 'Earth'; Expected = 'Earth' }
      @{ Filter = 'ne*'  ; Expected = 'Neptune' }
      @{ Filter = 'ur*'  ; Expected = 'Uranus' }
      @{ Filter = 'm*'   ; Expected = 'Mercury', 'Mars' }
    ) {
      param ($Filter, $Expected)

      $planets = Get-Planet -Name $Filter
      $planets.Name | Should -Be $Expected
    }

    It "Given invalid parameter -Name 'Alpha Centauri', it returns `$null" {
      $planets = Get-Planet -Name 'Alpha Centauri'
      $planets | Should -Be $null
    }
  }
}
```

This code example lies a tiny bit, [find it annotated and production ready here](Examples/Planets).

Learn more about the [usage and syntax](https://github.com/Pester/Pester/wiki) on our wiki.

## Installation

Pester is compatible with Windows 10, 8, 7, Vista and even 2003. We are also working hard on making it run on Linux and MacOS.

Pester comes pre-installed with Windows 10, but we recommend updating, by running this PowerShell command _as administrator_:

```powershell
Install-Module -Name Pester -Force -SkipPublisherCheck
```

Not running Windows 10 or facing problems? See the [full installation and update guide](https://github.com/pester/Pester/wiki/Installation-and-Update).

## Features

### Test runner

Pester runs your tests and prints a nicely formatted output to the screen.

![test run output](doc/readme/output.PNG)

Command line output is not the only output option, Pester also integrates with Visual Studio Code, Visual Studio, and any tool that can consume nUnit XML output.

### Assertions

Pester comes with a suite of assertions that cover a lot of common use cases. Pester assertions range from very versatile, like `Should -Be`, to specialized like `Should -Exists`. Here is how you ensure that a file exists:

```powershell
Describe 'Notepad' {
    It 'Exists in Windows folder' {
        'C:\Windows\notepad.exe' | Should -Exist
    }
}
```

Learn more about assertion on [our wiki](https://github.com/pester/Pester/wiki/Should).

### Mocking

Pester has mocking built-in. Using mocks you can easily replace functions with empty implementation to avoid changing the real environment.

```powershell
function Remove-Cache {
    Remove-Item "$env:TEMP\cache.txt"
}

Describe 'Remove-Cache' {
    It 'Removes cached results from temp\cache.text' {
        Mock -CommandName Remove-Item -MockWith {}

        Remove-Cache

        Assert-MockCalled -CommandName Remove-Item -Times 1 -Exactly
    }
}
```

Learn more [about Mocking here](https://github.com/pester/Pester/wiki/Mock).

### Code coverage

Pester can measure how much of your code is covered by tests and export it to JaCoCo format that is easily understood by build servers.

![JaCoCo code coverage report](doc/readme/jacoco.PNG)

Learn more about [code coverage here](https://github.com/pester/Pester/wiki/Code-Coverage).

### Build server integration

Pester integrates nicely with TFS, AppVeyor, TeamCity, Jenkins and other CI servers.

Testing your scripts, and all pull requests on AppVeyor is extremely simple. Just commit this `appveyor.yml` file to your repository, and select your repository on the AppVeyor website:

```yml
version: 1.0.{build}
image: WMF 5
install:
- ps: choco install pester
build: off
test_script:
- ps: Invoke-Pester -EnableExit
```

See it [in action here!](https://ci.appveyor.com/project/nohwnd/planets)

Pester itself is build on the [community build server](build.powershell.org).

[![Build status](https://build.powershell.org/guestAuth/app/rest/builds/buildType:(id:Pester_TestPester)/statusIcon)](https://build.powershell.org/project.html?projectId=Pester&tab=projectOverview&guest=1)

## Further reading

Do you like what you see? Learn how to use Pester with our [Getting started guide](https://github.com/pester/Pester/wiki/Getting-started-with-Pester), and continue with some of the other [resources](https://github.com/pester/Pester/wiki/Articles-and-other-resources).

## Got questions?

Got questions or you just want to get in touch? Use our issues page or one of these channels:

[![Pester Twitter](doc/readme/twitter-64.PNG)](https://twitter.com/PSPester)
[![Pester on StackOverflow](doc/readme/stack-overflow-64.PNG)](https://stackoverflow.com/questions/tagged/pester)
[![Testing channel on Powershell Slack](doc/readme/slack-64.PNG)](https://powershell.slack.com/messages/C03QKTUCS)
[![Pester Gitter](doc/readme/gitter-64.PNG)](https://gitter.im/pester/Pester?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)