public CourseDirectoryImportFunctions(
     ICourseDirectoryDataService courseDirectoryDataService,
     ITableStorageService tableStorageService)
 {
     _courseDirectoryDataService = courseDirectoryDataService ?? throw new ArgumentNullException(nameof(courseDirectoryDataService));
     _tableStorageService        = tableStorageService ?? throw new ArgumentNullException(nameof(tableStorageService));
 }
        public static CourseDirectoryImportFunctions BuildCourseDirectoryImportFunctions(
            ICourseDirectoryDataService courseDirectoryDataService = null,
            ITableStorageService tableStorageService = null)
        {
            courseDirectoryDataService ??= Substitute.For <ICourseDirectoryDataService>();
            tableStorageService ??= Substitute.For <ITableStorageService>();

            return(new CourseDirectoryImportFunctions(courseDirectoryDataService, tableStorageService));
        }