System.IO.Abstractions.TestingHelpers.MockFileSystem.AddDirectory C# (CSharp) Method

        public void AddDirectory(string path)
        {
            var fixedPath = FixPath(path);
            var separator = XFS.Separator();

            lock (files)
            {
                if (FileExists(path) &&
                    (files[fixedPath].Attributes & FileAttributes.ReadOnly) == FileAttributes.ReadOnly)
                    throw new UnauthorizedAccessException(string.Format(CultureInfo.InvariantCulture, Properties.Resources.ACCESS_TO_THE_PATH_IS_DENIED, path));

                var lastIndex = 0;

                bool isUnc =
                    path.StartsWith(@"\\", StringComparison.OrdinalIgnoreCase) ||
                    path.StartsWith(@"//", StringComparison.OrdinalIgnoreCase);

                if (isUnc)
                {
                    //First, confirm they aren't trying to create '\\server\'
                    lastIndex = path.IndexOf(separator, 2, StringComparison.OrdinalIgnoreCase);
                    if (lastIndex < 0)
                        throw new ArgumentException(@"The UNC path should be of the form \\server\share.", "path");

                    /*
                     * Although CreateDirectory(@"\\server\share\") is not going to work in real code, we allow it here for the purposes of setting up test doubles.
                     * See PR https://github.com/tathamoddie/System.IO.Abstractions/pull/90 for conversation
                     */
                }

                while ((lastIndex = path.IndexOf(separator, lastIndex + 1, StringComparison.OrdinalIgnoreCase)) > -1)
                {
                    var segment = path.Substring(0, lastIndex + 1);
                    if (!directory.Exists(segment))
                    {
                        files[segment] = new MockDirectoryData();
                    }
                }

                var s = path.EndsWith(separator, StringComparison.OrdinalIgnoreCase) ? path : path + separator;
                files[s] = new MockDirectoryData();
            }
        }

        public void TestCleanRecursive()
        {
            // Prepare the source and target directories and files.
            var fileSystem = new System.IO.Abstractions.TestingHelpers.MockFileSystem();
            fileSystem.AddDirectory(@"C:\Source\SubDirectory");
            fileSystem.AddFile(@"C:\Target\SubDirectory\File.txt", new MockFileData("Data"));

            // Run the test.
            Cleaner.CleanResult result = Cleaner.Clean(fileSystem, @"C:\Target", @"C:\Source");

            // Check the results
            Assert.IsFalse(fileSystem.File.Exists(@"C:\Target\SubDirectory\File.txt"));
        }