Code samples from Working Effectively with Unit Tests (https://leanpub.com/wewut)

wewut-tests.cs

[TestClass]
public class CustomerTest
{
    private const string DavidName = "David";
    private const string JohnName = "John";
    private const string PatName = "Pat";
    private const string SteveName = "Steve";
    private readonly Customer[] _customers;
    private readonly Customer _david;
    private readonly Customer _john;
    private readonly Customer _pat;
    private readonly Customer _steve;

    public CustomerTest()
    {
        _david = ObjectMother.CustomerWithNoRentals(DavidName);
        _john = ObjectMother.CustomerWithOneNewRelease(JohnName);
        _pat = ObjectMother.CustomerWithOneOfEachRentalGenre(PatName);
        _steve = ObjectMother.CustomerWithOneNewReleaseAndOneRegular(SteveName);
        _customers = new[] {_david, _john, _steve, _pat};
    }

    [TestMethod]
    public void GetName()
    {
        Assert.AreEqual(DavidName, _david.GetName());
        Assert.AreEqual(JohnName, _john.GetName());
        Assert.AreEqual(SteveName, _steve.GetName());
        Assert.AreEqual(PatName, _pat.GetName());
    }

    [TestMethod]
    public void Statement()
    {
        foreach (var t in _customers)
        {
            var expected = ExpStatement(@"Rental record for {0}
{1}Amount owed is {2}
You earned {3} frequent renter points",
                t, RentalInfo("\t", "", t.GetRentals()));
            var actual = t.Statement();
            Assert.AreEqual(expected, actual);
        }
    }

    [TestMethod]
    public void HtmlStatement()
    {
        foreach (var customer in _customers)
        {
            Assert.AreEqual(
                ExpStatement(
                    "<h1>Rental record for " + "<em>{0}</em></h1>\r\n{1}" + "<p>Amount owed is <em>{2}</em>" +
                    "</p>\r\n<p>You earned <em>{3}" + " frequent renter points</em></p>",
                    customer,
                    RentalInfo("<p>", "</p>", customer.GetRentals())),
                customer.HtmlStatement());
        }
    }

    [TestMethod]
    [ExpectedException(typeof (ArgumentException))]
    public void InvalidTitle()
    {
        ObjectMother.CustomerWithNoRentals("Bob")
            .AddRental(new Rental(new Movie("Crazy, Stupid, Love.", Movie.Genre.Unknown), 4));
    }

    public static string RentalInfo(string startsWith, string endsWith, List<Rental> rentals)
    {
        var result = "";
        foreach (var rental in rentals)
            result += string.Format("{0}{1} {2}{3}\r\n", startsWith, rental.GetMovie().GetTitle(), rental.GetCharge(),
                endsWith);
        return result;
    }

    public static string ExpStatement(string formatStr, Customer customer, string rentalInfo)
    {
        return string.Format(formatStr, customer.GetName(), rentalInfo, customer.GetTotalCharge(),
            customer.GetTotalPoints());
    }
}

public class ObjectMother
{
    public static Customer CustomerWithOneOfEachRentalGenre(string name)
    {
        var result = CustomerWithOneNewReleaseAndOneRegular(name);
        result.AddRental(new Rental(new Movie("Lion King", Movie.Genre.Children), 3));
        return result;
    }

    public static Customer CustomerWithOneNewReleaseAndOneRegular(string n)
    {
        var result = CustomerWithOneNewRelease(n);
        result.AddRental(new Rental(new Movie("Scarface", Movie.Genre.Regular), 3));
        return result;
    }

    public static Customer CustomerWithOneNewRelease(string name)
    {
        var result = CustomerWithNoRentals(name);
        result.AddRental(new Rental(new Movie("Godfather 4", Movie.Genre.NewRelease), 3));
        return result;
    }

    public static Customer CustomerWithNoRentals(string name)
    {
        return new Customer(name);
    }
}

wewut.cs

public class Customer
{
    private readonly string _name;
    private readonly List<Rental> _rentals = new List<Rental>();

    public Customer(string name)
    {
        _name = name;
    }

    public override string ToString()
    {
        return GetName();
    }

    public string GetName()
    {
        return _name;
    }

    public List<Rental> GetRentals()
    {
        return _rentals;
    }

    public void AddRental(Rental rental)
    {
        _rentals.Add(rental);
    }

    public string Statement()
    {
        var result = "Rental record for " + GetName() + "\r\n";
        foreach (var rental in _rentals) result += "\t" + rental.GetLineItem() + "\r\n";
        result += "Amount owed is " + GetTotalCharge() + "\r\n" + "You earned " + GetTotalPoints() +
                  " frequent renter points";
        return result;
    }

    public string HtmlStatement()
    {
        var result = "<h1>Rental record for <em>" + GetName() + "</em></h1>\r\n";
        foreach (var rental in _rentals) result += "<p>" + rental.GetLineItem() + "</p>\r\n";
        result += "<p>Amount owed is <em>" + GetTotalCharge() + "</em></p>\r\n" + "<p>You earned <em>" +
                  GetTotalPoints() +
                  " frequent renter points</em></p>";
        return result;
    }

    public double GetTotalCharge()
    {
        return _rentals.Sum(rental => rental.GetCharge());
    }

    public int GetTotalPoints()
    {
        return _rentals.Sum(rental => rental.GetPoints());
    }
}

public class Rental
{
    private readonly int _daysRented;
    private readonly Movie _movie;

    public Rental(Movie movie, int daysRented)
    {
        _movie = movie;
        _daysRented = daysRented;
    }

    public Movie GetMovie()
    {
        return _movie;
    }

    public int GetDaysRented()
    {
        return _daysRented;
    }

    public double GetCharge()
    {
        return _movie.GetCharge(_daysRented);
    }

    public virtual int GetPoints()
    {
        return _movie.GetPoints(_daysRented);
    }

    public string GetLineItem()
    {
        return _movie.GetTitle() + "\t" + GetCharge();
    }
}

public class Movie
{
    public enum Genre
    {
        Regular,
        NewRelease,
        Children,
        Unknown
    }

    private readonly string _title;
    private Price _price;

    public Movie(
        string title, Genre priceCode)
    {
        _title = title;
        SetPriceCode(priceCode);
    }

    public string GetTitle()
    {
        return _title;
    }

    private void SetPriceCode(Genre priceCode)
    {
        switch (priceCode)
        {
            case Genre.Children:
                _price = new ChildrensPrice();
                break;
            case Genre.NewRelease:
                _price = new NewReleasePrice();
                break;
            case Genre.Regular:
                _price = new RegularPrice();
                break;
            default:
                throw new ArgumentException("invalid price code");
        }
    }

    public double GetCharge(int daysRented)
    {
        return _price.GetCharge(daysRented);
    }

    public int GetPoints(int daysRented)
    {
        return _price.GetPoints(daysRented);
    }
}

public abstract class Price
{
    public abstract double GetCharge(int daysRented);

    public virtual int GetPoints(int daysRented)
    {
        return 1;
    }
}

public class ChildrensPrice : Price
{
    public override double GetCharge(int daysRented)
    {
        var amount = 1.5;
        if (daysRented > 3) amount += (daysRented - 3)*1.5;
        return amount;
    }
}

public class RegularPrice : Price
{
    public override double GetCharge(int daysRented)
    {
        double amount = 2;
        if (daysRented > 2) amount += (daysRented - 2)*1.5;
        return amount;
    }
}

public class NewReleasePrice : Price
{
    public override double GetCharge(int daysRented)
    {
        return daysRented*3;
    }

    public override int GetPoints(int daysRented)
    {
        if (
            daysRented > 1) return 2;
        return 1;
    }
}