using System;

using Microsoft.VisualStudio.TestTools.UnitTesting;

public class Program

{

    public static void Main()

    {

        var tests = new CalculatorTests();

        tests.Sum_WhenPassingTwoPositiveIntegerNumbers_AssertSumIsCorrect();

        Console.WriteLine("Sum_WhenPassingTwoPositiveIntegerNumbers_AssertSumIsCorrect: Passed!");

    }       

}

​

public sealed class CalculatorTests

{

    public void Sum_WhenPassingTwoPositiveIntegerNumbers_AssertSumIsCorrect() 

    {       

        Calculator c = new Calculator();

        var sum = c.Sum(1, 2);

        Assert.AreEqual(3, sum);

    }

}

​

public sealed class Calculator {

    public int Sum(int a, int b) 

    {

        var logger = new DatabaseLogger();

        logger.Log("Method Sum called.");

        return a + b;

    }

}

​

public sealed class DatabaseLogger

{

    public void Log(string message) {

        //Trying to write the log into the Database...

        throw new Exception("The database is offline. You shouldn't be calling the database from a Unit Test!");

    }

}