Unable to create unit test for my code

Question

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Collections;

using System.IO;

namespace Testnames

{

public class Sorting

{

public static void sortFile(string fname)

{

//Calling file using string parameter

string name = fname;

if (fname.Equals("names.txt"))

{

ArrayList names = new ArrayList();

///Creating a new streamreader object to read the existing text file

StreamReader sr;

try

{

sr = new StreamReader(name);

string line;

//Reading a file and putting the content in names ArrayList

while (!sr.EndOfStream)

{

line = sr.ReadLine();

names.Add(line);

}

Console.WriteLine("sort-names" + " " + @"names.txt");

// Pause the application so the user can read the information on the screen

Console.ReadLine();

//Sorting Array

names.Sort();

string outfile = @"names-sorted.txt";

//Checking whether the file is already in the system

checkofile(outfile);

//Creating new text file

using (System.IO.StreamWriter file = new System.IO.StreamWriter(@"names-sorted.txt", false))

{

foreach (string c in names)

{

Console.WriteLine(c);

//Writing to the new text file

file.WriteLine(c);

}

}

//Final output

Console.WriteLine("Finished: created names-sorted.txt");

}

catch (Exception e)

{

Console.WriteLine("Sorry! File Not Found");

Console.ReadLine();

}

}

else

{

Console.WriteLine("Sorry! Please check file name");

Console.ReadLine();

}

}

public static void checkofile(string ofile)

{

if (File.Exists(ofile))

{

System.IO.File.WriteAllText(ofile, string.Empty); //If there is already some content, clear it

}

else

{

File.Create(ofile);

Console.WriteLine("New File Created");

Console.ReadLine();

}

}

static void Main(string[] args)

{

string filename = "names.txt";

Sorting.sortFile(filename);

}

}

}