What's the default PSHost implementation (for use in a RunspacePool)?

Question

I'm trying to create a RunspacePool with an initial session state and a count of min/max runspaces. However, the only constructor on RunspaceFactory that supports all those parameters also requires a PSHost:

public static System.Management.Automation.Runspaces.RunspacePool CreateRunspacePool (
  int minRunspaces,
  int maxRunspaces,
  System.Management.Automation.Runspaces.RunspaceConnectionInfo connectionInfo,
  System.Management.Automation.Host.PSHost host);

Passing null for host crashes at runtime:

PSArgumentNullException: Cannot process argument because the value of argument "host" is null. Change the value of argument "host" to a non-null value.

What default implementation of PSHost can I pass here? It's an abstract class.

---

C# configuration:

<PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net8.0-windows10.0.19041.0</TargetFramework>
    <TargetPlatformMinVersion>10.0.17763.0</TargetPlatformMinVersion>
    <RootNamespace>MyRoot</RootNamespace>
    <ApplicationManifest>app.manifest</ApplicationManifest>
    <Platforms>x86;x64;ARM64</Platforms>
    <RuntimeIdentifiers>win-x86;win-x64;win-arm64</RuntimeIdentifiers>
    <UseWinUI>true</UseWinUI>
    <Nullable>enable</Nullable>
</PropertyGroup>

Answer 1

There is no default implementation of PSHost, but it is straightforward to make a "bare" one:

private class BareHost : PSHost
{
    public override string Name { get; } = "BareHost";
    public override Version Version { get; } = new Version(1, 0);
    public override Guid InstanceId { get; } = Guid.NewGuid();
    public override PSHostUserInterface UI { get; } = null;
    public override CultureInfo CurrentCulture { get; } = CultureInfo.CurrentCulture;
    public override CultureInfo CurrentUICulture { get; } = CultureInfo.CurrentUICulture;

    public override void EnterNestedPrompt()
    {
        throw new NotImplementedException();
    }

    public override void ExitNestedPrompt()
    {
        throw new NotImplementedException();
    }

    public override void NotifyBeginApplication()
    {
        // no-op
    }

    public override void NotifyEndApplication()
    {
        // no-op
    }

    public override void SetShouldExit(int exitCode)
    {
        // no-op
    }
}

Usage:

var initialSessionState = InitialSessionState.CreateDefault();

// Customize your session state...
// initialSessionState.ImportPSModule(new[] { "MyModule" });

using var pool = RunspaceFactory.CreateRunspacePool(
  minRunspaces: 1, 
  maxRunspaces: 3, 
  initialSessionState: initialSessionState, 
  host: new BareHost());