Behavior-Driven Development with NBehave

/* Copyright (C) Dmitri Nesteruk */

using System;

namespace ConsoleApplication1
{
  using NBehave.Narrator.Framework;
  using NBehave.Spec.MbUnit;
  using MbUnit.Framework;

  using That = MbUnit.Framework.TestAttribute;
  using Describe = MbUnit.Framework.CategoryAttribute;
  using For = MbUnit.Framework.CategoryAttribute;
  using Wrote = MbUnit.Framework.DescriptionAttribute;
  using Should = MbUnit.Framework.DescriptionAttribute;
  using Full = MbUnit.Framework.MultipleAssertsAttribute;

  [
    Author("Dmitri", "dmitrinesteruk@gmail.com"),
    Wrote("Account operation tests"),
    TestsOn(typeof(Account)),
    For("Banking system")
  ]
  public class AccountTest : SpecBase
  {
    public Account account;
    public Account account2;

    [SetUp]
    public void Initialize_before_each_test()
    {
      account = new Account();
      account2 = new Account { Balance = 100 };
    }

    [Full, Story, That, Should("Increase account balance when money is deposited")]
    public void Deposit_should_increase_account_balance()
    {
      Story story = new Story("Deposit");
      story.AsA("User")
        .IWant("The bank account balance to increase by the amount deposited")
        .SoThat("I can deposit money");

      story.WithScenario("Money deposit")
        .Given("My bank account is empty", () => { account.Balance = 0; })
        .When("I deposit 100 units", () => account.Deposit(100))
        .Then("The account balance should be 100", () => account.Balance.ShouldEqual(100));

      story.WithScenario("Negative amount deposit")
        .Given("My bank account is empty", () => { account.Balance = 0; })
        .When("I try to deposit a negative amount", () => { })
        .Then("I get an exception",
              () => typeof(Exception).ShouldBeThrownBy(() => account.Deposit(-100)))
        .And("My bank account balance is unchanged",
             () => account.Balance.ShouldEqual(0));
    }

    [Story, That, Should("Decrease account balance when money is withdrawn")]
    public void Withdrawal_should_decrease_account_balance()
    {
      Story story = new Story("Withdrawal");
      story.AsA("User")
        .IWant("To be able to withdraw money if I have it")
        .SoThat("I can buy things");

      story.WithScenario("Withdrawal with empty bank account")
        .Given("My bank is empty", () => { account.Balance = 0; })
        .When("I try to withdraw money", () => {})
        .Then("I get an exception", () =>
              typeof(Exception).ShouldBeThrownBy(() => account.Withdraw(100)))
        .And("I still have an empty bank account", () => account.Balance.ShouldEqual(0));

      story.WithScenario("Withdrawal with sufficient balance")
        .Given("I've got 100 dollars in my bank account", () => { account.Balance = 100; })
        .When("I try to withdraw 50 dollars", () => account.Withdraw(50))
        .Then("I have 50 dollars left in the account",
              () => account.Balance.ShouldEqual(50));
    }

    [Story, That, Should("Transfer money from one account to another")]
    public void Transfer_should_move_money_from_one_account_to_another()
    {
      Story story = new Story("Tranfer");
      story.AsA("User").IWant("The transfer feature to be atomic")
        .SoThat("My money isn't lost");

      story.WithScenario("Valid transfer")
        .Given("I have 100 dollars", () => { account.Balance = 100; })
        .And("You have 100 dollars", () => { account2.Balance = 100; })
        .When("I give you 50 dollars",
              () => Assert.DoesNotThrow(() => Account.Transfer(account, account2, 50)))
        .Then("I have 50 dollars left", () => account.Balance.ShouldEqual(50))
        .And("You have 150 dollars", () => account2.Balance.ShouldEqual(150));
    }
  }
}