These tests are completely Linux specific.

Every test class must belong to [Collection("AssemblyLoadContext")]. This ensures that PowerShell's AssemblyLoadContext is initialized before any other code is executed. When this is not the case, late initialization fails with System.InvalidOperationException : Binding model is already locked for the AppDomain and cannot be reset.

Having every class in the same collection is as close to an xUnit global init hook as can be done.

Go to the top level of the PowerShell repository and run: Start-PSxUnit inside a self-hosted copy of PowerShell.