Testing a slow request (like a bad performing DB query)

SlowRequestController.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;

namespace wwwlearn.Controllers
{
    [Route("")]
    public class ValuesController : Controller
    {
        // GET api/values
        [HttpGet("test1")]
        public IEnumerable<string> Get()
        {
            return new string[] { "value1", "value2" };
        }

        [HttpGet("slowtest/")]
        [HttpGet("slowtest/{delayTimeInSeconds:int}")]
        public async Task<string> Get(CancellationToken cancellationToken, 
            int delayTimeInSeconds = 10)
        {
            var stopwatch = Stopwatch.StartNew();

            var message = "Starting to do slow work";

            await Task.Run(async () =>
            {
                await Task.Delay(delayTimeInSeconds * 1000, cancellationToken);
                message = $"Finished slow delay of {delayTimeInSeconds} seconds.";
            }, cancellationToken);
            
            stopwatch.Stop();

            if (cancellationToken.IsCancellationRequested)
            {
                message = $"request was cancelled after {stopwatch.ElapsedMilliseconds:N0} milliseconds";
            }
            
            return message;
        }
    }
}