Test without Shouldly

HelpersTest.cs

using Xunit;

namespace Problems.Tests
{
    public class HelpersTess
    {
        [Fact]
        public void Sum_ShouldBeSuccess()
        {
            // Helpers.Sum(1, 2).ShouldBe(3);
            Assert.Equal(3, Helpers.Sum(1, 2));
        }
    }
}