Add support for fake input in asciicast recordings

* Fixes a bug with `SelectionPrompt` and page size.
* Allow `IAnsiConsoleInput` to return `null`.

resources/scripts/Generator/Commands/AsciiCast/Samples/InputSample.cs

@@ -0,0 +1,97 @@
+using DocExampleGenerator;
+using Spectre.Console;
+
+namespace Generator.Commands.Samples
+{
+    internal class InputSample : BaseSample
+    {
+        public override void Run(IAnsiConsole console)
+        {
+            var age = 0;
+            var name = string.Empty;
+            var sport = string.Empty;
+            var password = string.Empty;
+            var color = string.Empty;
+
+            console.DisplayThenType(c => name = AskName(c), "Peter F↲");
+            console.DisplayThenType(c => sport = AskSport(c), "football↲¦¦¦¦Hockey↲");
+            console.DisplayThenType(c => age = AskAge(c), "Forty↲¦¦¦¦40↲");
+            console.DisplayThenType(c => password = AskPassword(c), "hunter2↲");
+            console.DisplayThenType(c => color = AskColor(c), "↲");
+
+            AnsiConsole.Render(new Rule("[yellow]Results[/]").RuleStyle("grey").LeftAligned());
+            AnsiConsole.Render(new Table().AddColumns("[grey]Question[/]", "[grey]Answer[/]")
+                .RoundedBorder()
+                .BorderColor(Color.Grey)
+                .AddRow("[grey]Name[/]", name)
+                .AddRow("[grey]Favorite sport[/]", sport)
+                .AddRow("[grey]Age[/]", age.ToString())
+                .AddRow("[grey]Password[/]", password)
+                .AddRow("[grey]Favorite color[/]", string.IsNullOrEmpty(color) ? "Unknown" : color));
+        }
+
+        private static string AskName(IAnsiConsole console)
+        {
+            console.WriteLine();
+            console.Write(new Rule("[yellow]Strings[/]").RuleStyle("grey").LeftAligned());
+            var name = console.Ask<string>("What's your [green]name[/]?");
+            return name;
+        }
+
+
+        private static string AskSport(IAnsiConsole console)
+        {
+            console.WriteLine();
+            console.Write(new Rule("[yellow]Choices[/]").RuleStyle("grey").LeftAligned());
+
+            return console.Prompt(
+                new TextPrompt<string>("What's your [green]favorite sport[/]?")
+                    .InvalidChoiceMessage("[red]That's not a sport![/]")
+                    .DefaultValue("Sport?")
+                    .AddChoice("Soccer")
+                    .AddChoice("Hockey")
+                    .AddChoice("Basketball"));
+        }
+
+        private static int AskAge(IAnsiConsole console)
+        {
+            console.WriteLine();
+            console.Write(new Rule("[yellow]Integers[/]").RuleStyle("grey").LeftAligned());
+
+            return console.Prompt(
+                new TextPrompt<int>("How [green]old[/] are you?")
+                    .PromptStyle("green")
+                    .ValidationErrorMessage("[red]That's not a valid age[/]")
+                    .Validate(age =>
+                    {
+                        return age switch
+                        {
+                            <= 0 => ValidationResult.Error("[red]You must at least be 1 years old[/]"),
+                            >= 123 => ValidationResult.Error("[red]You must be younger than the oldest person alive[/]"),
+                            _ => ValidationResult.Success(),
+                        };
+                    }));
+        }
+
+        private static string AskPassword(IAnsiConsole console)
+        {
+            console.WriteLine();
+            console.Write(new Rule("[yellow]Secrets[/]").RuleStyle("grey").LeftAligned());
+
+            return console.Prompt(
+                new TextPrompt<string>("Enter [green]password[/]?")
+                    .PromptStyle("red")
+                    .Secret());
+        }
+
+        private static string AskColor(IAnsiConsole console)
+        {
+            console.WriteLine();
+            console.Write(new Rule("[yellow]Optional[/]").RuleStyle("grey").LeftAligned());
+
+            return console.Prompt(
+                new TextPrompt<string>("[grey][[Optional]][/] What is your [green]favorite color[/]?")
+                    .AllowEmpty());
+        }
+    }
+}