public void AddFiles_ForRequestFiles_ReturnActionResult()
        {
            // Arrange
            InitializeAddFiles();
            var controller = new GroupController();

            // Act
            var result = controller.AddFiles() as JsonResult;

            // Assert
            result.ShouldSatisfyAllConditions(
                () => result.ShouldNotBeNull(),
                () => result.Data.ShouldNotBeNull());
        }