如果仅包含文本文件，则删除文件夹

我一直在使用它来删除空文件夹，它非常适合我的需求。如果文件夹只包含一个SINGLE.txt文件，我需要添加一个规定才能删除该文件夹。如果目录仅包含.txt文件，我应该如何更改此语法以仍然删除该目录？

static void Main(string[] args)
{
    string path = @"C:'Test'";
}
public static void processDirectory(string startLocation)
{
    foreach (var directory in Directory.GetDirectories(startLocation))
    {
        processDirectory(directory);
        if (Directory.GetFiles(directory).Length == 0 && Directory.GetDirectories(directory).Length == 0)
        {
            Directory.Delete(directory, false);
        }
    }           
}

编辑

这会产生语法错误，但我认为这正是我试图实现的原因

if (Directory.GetFiles(Path.GetExtension) == ".txt")

public static void processDirectory(string startLocation)
{
    foreach (var directory in Directory.GetDirectories(startLocation))
    {
        processDirectory(directory);
        var aFiles = Directory.GetFiles(directory);
        var noFiles = aFiles.Length == 0 || (aFiles.Length == 1 && aFiles.Count(file => Path.GetExtension(file) == ".txt") == 1);
        if (noFiles && Directory.GetDirectories(directory).Length == 0)
        {
            Directory.Delete(directory, true);
        }
    }           
}