Unit testing NHibernate UserTypes

Question

Does anyone have a good approach towards unit testing their UserTypes?

By way of example, I have an object in my model called DateRange, which has a DatePoint start and DatePoint end. In addition to making range type operations available for two DateTimes, these objects let me adjust the precision for the task at hand (i.e., Day, Hour, Minute, etc.). When stored to the db for an application I'm working on, I just need to store the start and end as DateTime, no nulls allowed. I can't think of how to map this without a UserType, so I have:

/// <summary>User type to deal with <see cref="DateRange"/> persistence for time sheet tracking.</summary>
public class TimePeriodType : IUserType
{

    public SqlType[] SqlTypes {
        get {
            var types = new SqlType[2];
            types[0] = new SqlType(DbType.DateTime);
            types[1] = new SqlType(DbType.DateTime);
            return types;  

        }
    }

    public Type ReturnedType
    {
        get { return typeof(DateRange); }
    }

    /// <summary>Just return <see cref="DateRange.Equals(object)"/></summary>
    public new bool Equals(object x, object y)
    {
        return x != null && x.Equals(y);
    }

    /// <summary>Just return <see cref="DateRange.GetHashCode"/></summary>
    public int GetHashCode(object x)
    {
        return x.GetHashCode();
    }

    public object NullSafeGet(IDataReader rs, string[] names, object owner)
    {
        var start = (DateTime)NHibernateUtil.DateTime.NullSafeGet(rs, names[0]);
        var end = (DateTime)NHibernateUtil.DateTime.NullSafeGet(rs, names[1]);

        return new DateRange(start, end, TimeSlice.Minute);
    }

    public void NullSafeSet(IDbCommand cmd, object value, int index) {
        Check.RequireNotNull<DateRange>(value);
        Check.RequireArgType<DateRange>(value);
        var dateRange = ((DateRange)value);

        NHibernateUtil.DateTime.NullSafeSet(cmd, dateRange.Start, index);
        NHibernateUtil.DateTime.NullSafeSet(cmd, dateRange.End, index);
    }

    public object DeepCopy(object value) {
        Check.RequireNotNull<DateRange>(value);
        Check.RequireArgType<DateRange>(value);
        var dateRange = ((DateRange) value);

        return new DateRange(dateRange.Start, dateRange.End);
    }

    public bool IsMutable
    {
        get { return false; }
    }

    public object Replace(object original, object target, object owner) {
        //because it is immutable so we can just return it as is  
        return original;
    }

    public object Assemble(object cached, object owner) {
        //Used for caching, as it is immutable we can just return it as is  
        return cached;
    }

    public object Disassemble(object value) {
        //Used for caching, as it is immutable we can just return it as is  
        return value;
    }
}

}

Now I'm looking for a way to prove it works. Thanks in advance!

Cheers, Berryl

Answer 1

I was thinking I could mock / fake some of the dependencies here, but wound up deciding the best way to do this was by using a database.

Some things I learned along the way:

1) it's worth the effort when learning NHibernate techniques to have a dedicated set of tools including a way to quickly configure a db and test fixture for it (the same kinds of agile tools you'll need for everything else, really) and a dedicated test lab that you don't have an emotional investment in.

2) mocks do not lend themselves to interfaces you don't own, like IDataReader.

Cheers

Answer 2

I created a user type for System.Drawing.Color, and here is how I unit tested it with MSTest and Moq.

ColorUserType.cs:

public class ColorUserType : IUserType
{
    public object Assemble( object cached, object owner )
    {
     return cached;
    }

    public object DeepCopy( object value )
    {
     return value;
    }

    public object Disassemble( object value )
    {
     return value;
    }

    public new bool Equals( object x, object y )
    {
     if(ReferenceEquals(x, y ) )
     {
      return true;
     }
     if( x == null || y == null )
     {
      return false;
     }
     return x.Equals( y );
    }

    public int GetHashCode( object x )
    {
     return x == null ? typeof( Color ).GetHashCode() + 473 : x.GetHashCode();
    }

    public bool IsMutable
    {
     get 
     {
      return true;
     }
    }

    public object NullSafeGet( IDataReader rs, string[] names, object owner )
    {
     var obj = NHibernateUtil.String.NullSafeGet( rs, names[0] );
     if( obj == null )
     {
      return null;
     }
     return ColorTranslator.FromHtml( (string)obj );
    }

    public void NullSafeSet( IDbCommand cmd, object value, int index )
    {
     if( value == null )
     {
      ( (IDataParameter)cmd.Parameters[index] ).Value = DBNull.Value;
     }
     else
     {
      ( (IDataParameter)cmd.Parameters[index] ).Value = ColorTranslator.ToHtml( (Color)value );
     }
    }

    public object Replace( object original, object target, object owner )
    {
     return original;
    }

    public Type ReturnedType
    {
     get
     {
      return typeof( Color );
     }
    }

    public SqlType[] SqlTypes
    {
     get
     {
      return new[] { new SqlType( DbType.StringFixedLength ) };
     }
    }
}

ColorUserTypeTests.cs

    [TestClass]
    public class ColorUserTypeTests
    {
     public TestContext TestContext { get; set; }

     [TestMethod]
     public void AssembleTest()
     {
      var color = Color.Azure;
      var userType = new ColorUserType();
      var val = userType.Assemble( color, null );
      Assert.AreEqual( color, val );
     }

     [TestMethod]
     public void DeepCopyTest()
     {
      var color = Color.Azure;
      var userType = new ColorUserType();
      var val = userType.DeepCopy( color );
      Assert.AreEqual( color, val );
     }

     [TestMethod]
     public void DissasembleTest()
     {
      var color = Color.Azure;
      var userType = new ColorUserType();
      var val = userType.Disassemble( color );
      Assert.AreEqual( color, val );
     }

     [TestMethod]
     public void EqualsTest()
     {
      var color1 = Color.Azure;
      var color2 = Color.Bisque;
      var color3 = Color.Azure;
      var userType = new ColorUserType();

      var obj1 = (object)color1;
      var obj2 = obj1;

      Assert.IsFalse( userType.Equals( color1, color2 ) );
      Assert.IsTrue( userType.Equals( color1, color1 ) );
      Assert.IsTrue( userType.Equals( color1, color3 ) );
      Assert.IsFalse( userType.Equals( color1, null ) );
      Assert.IsFalse( userType.Equals( null, color1 ) );
      Assert.IsTrue( userType.Equals( null, null ) );
      Assert.IsTrue( userType.Equals( obj1, obj2 ) );
     }

     [TestMethod]
     public void GetHashCodeTest()
     {
      var color = Color.Azure;
      var userType = new ColorUserType();

      Assert.AreEqual( color.GetHashCode(), userType.GetHashCode( color ) );
      Assert.AreEqual( typeof( Color ).GetHashCode() + 473, userType.GetHashCode( null ) );
     }

     [TestMethod]
     public void IsMutableTest()
     {
      var userType = new ColorUserType();
      Assert.IsTrue( userType.IsMutable );
     }

     [TestMethod]
     public void NullSafeGetTest()
     {
      var dataReaderMock = new Mock();
      dataReaderMock.Setup( m => m.GetOrdinal( "white" ) ).Returns( 0 );
      dataReaderMock.Setup( m => m.IsDBNull( 0 ) ).Returns( false );
      dataReaderMock.Setup( m => m[0] ).Returns( "#ffffff" );

      var userType = new ColorUserType();
      var val = (Color)userType.NullSafeGet( dataReaderMock.Object, new[] { "white" }, null );

      Assert.AreEqual( "ffffffff", val.Name, "The wrong color was returned." );

      dataReaderMock.Setup( m => m.IsDBNull( It.IsAny() ) ).Returns( true );
      Assert.IsNull( userType.NullSafeGet( dataReaderMock.Object, new[] { "black" }, null ), "The color was not null." );

      dataReaderMock.VerifyAll();
     }

     [TestMethod]
     public void NullSafeSetTest()
     {
      const string color = "#ffffff";
      const int index = 0;

      var mockFactory = new MockFactory( MockBehavior.Default );

      var parameterMock = mockFactory.Create();
      parameterMock.SetupProperty( p => p.Value, string.Empty );

      var parameterCollectionMock = mockFactory.Create();
      parameterCollectionMock.Setup( m => m[0] ).Returns( parameterMock.Object );

      var commandMock = mockFactory.Create();
      commandMock.Setup( m => m.Parameters ).Returns( parameterCollectionMock.Object );

      var userType = new ColorUserType();

      userType.NullSafeSet( commandMock.Object, ColorTranslator.FromHtml( color ), index );
      Assert.AreEqual( 0, string.Compare( (string)( (IDataParameter)commandMock.Object.Parameters[0] ).Value, color, true ) );

      userType.NullSafeSet( commandMock.Object, null, index );
      Assert.AreEqual( DBNull.Value, ( (IDataParameter)commandMock.Object.Parameters[0] ).Value );

      mockFactory.VerifyAll();
     }

     [TestMethod]
     public void ReplaceTest()
     {
      var color = Color.Azure;
      var userType = new ColorUserType();
      Assert.AreEqual( color, userType.Replace( color, null, null ) );
     }

     [TestMethod]
     public void ReturnedTypeTest()
     {
      var userType = new ColorUserType();
      Assert.AreEqual( typeof( Color ), userType.ReturnedType );
     }

     [TestMethod]
     public void SqlTypesTest()
     {
      var userType = new ColorUserType();
      Assert.AreEqual( 1, userType.SqlTypes.Length );
      Assert.AreEqual( new SqlType( DbType.StringFixedLength ), userType.SqlTypes[0] );
     }
    }