UnitTest.js

public class Calculator
{
    public int Add(int x, int y)
    {
        return x + y;
    }
}

[TestClass]
public class UnitTest1
{
    [TestMethod]
    public void UnitTest3ARule()
    {
        //Arrange
        var calc = new Calculator();
        int x = 10, y = 20;
        //Act
        int actual = calc.Add(x, y);
        //Assert
        int expected = 30;
        Assert.AreEqual(expected, actual);
    }
}