public string EnsureValidExtension(string file, OutputFormat outputFormat)
        {
            if (HasValidExtension(file, outputFormat))
            {
                return(file);
            }

            var validExtension = GetValidExtensions(outputFormat).First();

            if (!HasKnownExtension(file))
            {
                file = file + validExtension;
            }

            return(_pathUtil.ChangeExtension(file, validExtension));
        }