[Prompt] Invoke validators on default value

[w4po]

I have encountered a use case in which I'd like the Prompt to validate the default value. I want to verify whether a file exists based on the provided value/default value.

I've found that when a user simply presses Enter, the validation is not triggered:

var path = AnsiConsole.Prompt(
            new TextPrompt<string>("Enter [olive]file path[/]: ")
                .DefaultValue("emails.txt")
                .HideDefaultValue()
                .ValidationErrorMessage("[red]Wrong path, File does not exist![/]")
                .Validate(File.Exists));

Possible solution:

spectre.console/src/Spectre.Console/Prompts/TextPrompt.cs

Lines 138 to 144 in 63b940c

	if (DefaultValue != null)
	{
	var defaultValue = converter(DefaultValue.Value);
	console.Write(IsSecret ? defaultValue.Mask(Mask) : defaultValue, promptStyle);
	console.WriteLine();
	return DefaultValue.Value;
	}

Change to:

if (DefaultValue != null)
{
    var defaultValue = converter(DefaultValue.Value);
    console.Write(IsSecret ? defaultValue.Mask(Mask) : defaultValue, promptStyle);
    console.WriteLine();
    
    // Run all validators
    if (!ValidateResult(defaultValue , out var validationMessage))
    {
        console.MarkupLine(validationMessage);
        WritePrompt(console);
        continue;
    }
    
    return DefaultValue.Value;
}

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