PowerShell serialization has a list of known PowerShell types. When an object is deserialized containing a known type it tries to deserialize the object to that specific type and throws an exception if it can't succeed. SemanticVersion only exists in PSCore6 so when remoting from Windows PowerShell or importing clixml generated from PSCore6 that contains SemanticVersion, it fails. With this fix, it will be rehydrated as a "PSObject" with "Deseriealized.System.Management.Automation.SemanticVersion" in the 'TypeNames' in both Windows PowerShell and PowerShell Core.
Pester Testing Test Guide
Also see the Writing Pester Tests document.
Running Pester Tests
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.
Testing new powershell processes
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"
& $powershell -noprofile -command "ExampleCommand" | Should Be "ExampleOutput"
Portability
Some tests simply must be tied to certain platforms. Use Pester's
-Skip directive on an It statement to do this. For instance to run
the test only on Windows:
It "Should do something on Windows" -Skip:($IsLinux -Or $IsMacOS) { ... }
Or only on Linux and OS X:
It "Should do something on Linux" -Skip:$IsWindows { ... }
Pending
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.