Added Exists

ProcessFiles/Interfaces/IFile.cs

@@ -5,5 +5,6 @@ namespace ProcessFiles.Interfaces
     public interface IFile
     {
         public FileAttributes GetAttributes(string path);
+        public bool Exists(string? path);
     }
 }

ProcessFiles/Models/DefaultFile.cs

@@ -6,5 +6,6 @@ namespace ProcessFiles.Models
     public class DefaultFile : IFile
     {
         public FileAttributes GetAttributes(string path) => File.GetAttributes(path);
+        public bool Exists(string? path) => File.Exists(path);
     }
 }

ProcessFiles/ProcessFiles.cs

@@ -52,7 +52,7 @@ namespace ProcessFiles
 
         private bool IsValid(string path, string[] fileExtensions)
         {
-            if (!File.Exists(path))
+            if (!fileSystem.File.Exists(path))
             {
                 errors.Add($"{path} doesn't exist!");
                 return false;