using System;

using Xunit;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}

public class CalculatorTests

{

    [Fact]

    public void Add_WhenCalledWithTwoIntegers_ReturnsTheirSum()

    {

        // Arrange

        var calculator = new Calculator();

        // Act

        var result = calculator.Add(2, 3);

​

        // Assert

        Assert.Equal(5, result);

    }

​

    private class Calculator

    {

        public int Add(int a, int b)

        {

            return a + b;

        }

    }

}

​