code snippets for "Implementing a Value Object" post

s1.cs

  public class Address
  {
    public Address(string street, string city, string region,
      string postalCode, string country, string phoneNumber)
    {
      _street = StringValueOrEmptyString(street);
      _city = StringValueOrEmptyString(city);
      _region = StringValueOrEmptyString(region);
      _postalCode = StringValueOrEmptyString(postalCode);
      _country = StringValueOrEmptyString(country);
      _phoneNumber = StringValueOrEmptyString(phoneNumber);
    }
 
    private string StringValueOrEmptyString(string value)
    {
      return (value != null ? value : string.Empty);
    }
 
    private string _street;
 
    public string Street
    {
      get { return _street; }
    }
 
    private string _city;
 
    public string City
    {
      get { return _city; }
    }
 
    private string _region;
 
    public string Region
    {
      get { return _region; }
    }
 
    private string _postalCode;
 
    public string PostalCode
    {
      get { return _postalCode; }
    }
 
    private string _country;
 
    public string Country
    {
      get { return _country; }
    }
 
    private string _phoneNumber;
 
    public string PhoneNumber
    {
      get { return _phoneNumber; }
    }
  }
}

s2.cs

public override bool Equals(object obj)
{
  Address address = obj as Address;
 
  if (address != null)
  {
    return
      _street.Equals(address.Street) &&
      _city.Equals(address.City) &&
      _region.Equals(address.Region) &&
      _postalCode.Equals(address.PostalCode) &&
      _country.Equals(address.Country) &&
      _phoneNumber.Equals(address.PhoneNumber);
  }
 
  return base.Equals(obj);
}

s3.cs

public override int GetHashCode()
{
  return _street.GetHashCode() ^
       _city.GetHashCode() ^
       _region.GetHashCode() ^
       _postalCode.GetHashCode() ^
       _country.GetHashCode() ^
       _phoneNumber.GetHashCode();
}

s4.cs

public static bool operator ==(Address address1, Address address2)
{
  if (!object.ReferenceEquals(address1, null) && object.ReferenceEquals(address2, null))
  {
    return false;
  }
 
  if (object.ReferenceEquals(address1, null) && !object.ReferenceEquals(address2, null))
  {
    return false;
  }
 
  return address1.Equals(address2);
}
 
public static bool operator !=(Address address1, Address address2)
{
  return !(address1 == address2);
}

s5.cs

[TestFixture]
public class AddressTests
{
  private string _defaultStreet = "MyStreet 243";
  private string _defaultCity = "MyCity";
  private string _defaultRegion = "MyRegion";
  private string _defaultPostalCode = "12345";
  private string _defaultCountry = "MyCountry";
  private string _defaultPhoneNumber = "123-4567-89";
 
  [Test]
  public void TwoInstancesWithSameDataAreEqual()
  {
    Address address1 = CreateTestAddressWithDefaultData();
    Address address2 = CreateTestAddressWithDefaultData();
 
    Assert.AreEqual(address1, address2);
    Assert.That(address1 == address2);
  }
 
  [Test]
  public void TwoInstancesWithDifferentDataAreNotEqual()
  {
    Address address1 = CreateTestAddressWithDefaultData();
    Address address2 = new Address(_defaultStreet + "2", _defaultCity, _defaultRegion,
      _defaultPostalCode, _defaultCountry, _defaultPhoneNumber);
 
    Assert.AreNotEqual(address1, address2);
    Assert.That(address1 != address2);
  }
 
  [Test]
  public void NullAddressReferenceDoesntCrashWhenUsingEqualityOperator()
  {
    Address address1 = null;
    Address address2 = CreateTestAddressWithDefaultData();
 
    Assert.That(address1 != address2);
  }
 
  [Test]
  public void TwoInstancesWithSameDateReturnSameHashCode()
  {
    Address address1 = CreateTestAddressWithDefaultData();
    Address address2 = CreateTestAddressWithDefaultData();
 
    Assert.AreEqual(address1.GetHashCode(), address2.GetHashCode());
  }
 
  [Test]
  public void TwoInstancesWithDifferentDataDoNotReturnSameHashCode()
  {
    Address address1 = CreateTestAddressWithDefaultData();
    Address address2 = new Address(_defaultStreet + "2", _defaultCity, _defaultRegion,
      _defaultPostalCode, _defaultCountry, _defaultPhoneNumber);
 
    Assert.AreNotEqual(address1.GetHashCode(), address2.GetHashCode());
  }
 
  private Address CreateTestAddressWithDefaultData()
  {
    return new Address(_defaultStreet, _defaultCity, _defaultRegion,
      _defaultPostalCode, _defaultCountry, _defaultPhoneNumber);
  }
}