Also see the Writing Pester Tests document.

First, restore the correct version of Pester using Restore-PSPester.

Then, go to the top level of the PowerShell repository and run: Start-PSPester inside a self-hosted copy of PowerShell.

You can use Start-PSPester -Tests SomeTestSuite* to limit the tests run.

Any launch of a new powershell process must include -noprofile so that modified user and system profiles do not causes tests to fail. You also must take care to call the development copy of PowerShell, which is not the first one on the path.

Example:

    $powershell = Join-Path -Path $PsHome -ChildPath "pwsh"
    & $powershell -noprofile -command "ExampleCommand" | Should Be "ExampleOutput"

Some tests simply must be tied to certain platforms. Use Pester's -Skip directive on an It statement to do this. For instance to run the test only on Windows:

It "Should do something on Windows" -Skip:($IsLinux -Or $IsMacOS) { ... }

Or only on Linux and OS X:

It "Should do something on Linux" -Skip:$IsWindows { ... }

When writing a test that should pass, but does not, please do not skip or delete the test, but use It "Should Pass" -Pending to mark the test as pending, and file an issue on GitHub.