DD.WellWorkover.Cloud/AsbCloudWebApi/Controllers/Mock.cs

using Microsoft.AspNetCore.Mvc;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace AsbCloudWebApi.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class MockController : ControllerBase
    {
        /// <summary>
        /// получить статистику  
        /// </summary>
        [HttpGet("400")]
        [ProducesResponseType(typeof(ValidationProblemDetails), (int)System.Net.HttpStatusCode.BadRequest)]
        public IActionResult Get([FromQuery, Required]IDictionary<string, string> args)
        {
            var errors = new Dictionary<string, string[]>();
            
            foreach (var arg in args)
            {
                var countOfErrors = ((arg.Key + arg.Value).Length % 3) + 1;
                var errorsText = Enumerable.Range(0, countOfErrors)
                    .Select(i => $"{arg.Value} не соответствует критериям проверки № {i}");

                errors.Add(arg.Key, errorsText.ToArray());                
            }

            if (errors.Any())
            {
                var problem = new ValidationProblemDetails(errors);                
                return BadRequest(problem);
            }
            else
            {
                var problem = new ValidationProblemDetails { Detail = "at least one argument must be provided" };
                return BadRequest(problem);
            }
        }
    }
}