Практика «Benchmark»

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;
using NUnit.Framework;

namespace StructBenchmarking
{
    public class Benchmark : IBenchmark
    {
        public double MeasureDurationInMs(ITask task, int repetitionCount)
        {
            GC.Collect();
            GC.WaitForPendingFinalizers();

            task.Run();

            var stopwatch = Stopwatch.StartNew();
            for (var i = 0; i < repetitionCount; i++)
            {
                task.Run();
            }
            stopwatch.Stop();
            return stopwatch.ElapsedMilliseconds / (double)repetitionCount;
        }
    }

    [TestFixture]
    public class RealBenchmarkUsageSample
    {
        [Test]
        public void StringConstructorFasterThanStringBuilder()
        {
            var repetitionCount = 10_000;
            var stirngLength = 10_000;

            var sbTask = new StringBuilderTask(stirngLength);
            var scTask = new StringConstructorTask(stirngLength);

            var benchmark = new Benchmark();

            var actualSbMeasure = benchmark.MeasureDurationInMs(sbTask, repetitionCount);
            var actualScMeasure = benchmark.MeasureDurationInMs(scTask, repetitionCount);

            Assert.Less(actualScMeasure, actualSbMeasure);
        }
    }

    public class StringBuilderTask : ITask
    {
        private readonly int stringLength;
        private string result;

        public StringBuilderTask(int stringLength)
        {
            this.stringLength = stringLength;
        }

        public void Run()
        {
            var sb = new StringBuilder();

            for (var i = 0; i < stringLength; i++)
            {
                sb.Append('a');
            }

            result = sb.ToString();
        }
    }

    public class StringConstructorTask : ITask
    {
        private readonly int stringLength;
        private string result;

        public StringConstructorTask(int stringLength)
        {
            this.stringLength = stringLength;
        }

        public void Run()
        {
            result = new string('a', stringLength);
        }
    }
}