chore(custom-host): Add way to manage PromptForChoice

src/PowershellHarness/CustomHost.cs

@@ -121,6 +121,19 @@ public class CustomUiHost : PSHostUserInterface
 
 	public string Output => output.ToString();
 
+	private int? _nextChoiceOption;
+
+	/// <summary>
+	/// Sets the next choice option to be used on the next call to <see cref="PromptForChoice"/>.
+	///
+	/// You'll probably get the 
+	/// </summary>
+	/// <param name="choiceOption"></param>
+	public void SetNextPromptChoice(int choiceOption)
+	{
+		_nextChoiceOption = choiceOption;
+	}
+
 	public override Dictionary<string, PSObject> Prompt(string caption, string message, System.Collections.ObjectModel.Collection<FieldDescription> descriptions)
 	{
 		throw new NotImplementedException("Prompt is not implemented.  The script is asking for input, which is a problem since there's no console.  Make sure the script can execute without prompting the user for input.");
@@ -128,7 +141,14 @@ public class CustomUiHost : PSHostUserInterface
 
 	public override int PromptForChoice(string caption, string message, System.Collections.ObjectModel.Collection<ChoiceDescription> choices, int defaultChoice)
 	{
-		throw new NotImplementedException("PromptForChoice is not implemented.  The script is asking for input, which is a problem since there's no console.  Make sure the script can execute without prompting the user for input.");
+		if (_nextChoiceOption is null)
+		{
+			throw new NotImplementedException("PromptForChoice is not implemented.  The script is asking for input, which is a problem since there's no console.  Make sure the script can execute without prompting the user for input.");
+		}
+
+		var choiceReturn = _nextChoiceOption.Value;
+		_nextChoiceOption = null;
+		return choiceReturn;
 	}
 
 	public override PSCredential PromptForCredential(string caption, string message, string userName, string targetName, PSCredentialTypes allowedCredentialTypes, PSCredentialUIOptions options)