using System;

using NUnit.Framework;

​

public class Program

{

    public static void Main()

    {

        var tests = new BankAccountTests();

        tests.InitialBalance_ShouldBeZero();

        Console.WriteLine("All unit tests are OK");

    }

}

​

public class BankAccount

{

    public decimal Balance { get; private set; }

​

    public void Deposit(decimal amount)

    {

        if (amount <= 0)

            throw new ArgumentException("Deposit amount must be positive.");

        Balance += amount;

    }

​

    public void Withdraw(decimal amount)

    {

        if (amount > Balance)

            throw new InvalidOperationException("Insufficient funds.");

        if (amount <= 0)

            throw new ArgumentException("Withdrawal amount must be positive.");

​

        Balance -= amount;

    }

}

​

[TestFixture]

public class BankAccountTests

{

    [Test]

    public void InitialBalance_ShouldBeZero()

    {

        // Arrange

        var account = new BankAccount();

​

        // Act

        var balance = account.Balance;

​

        // Assert

        Assert.That(balance == 0);

    }

}

​