public void DataReference()
{
IEntity entity = new ContentEntity(0, "");
entity.AddData <DataInt>().A = 1;
DataReference <DataInt> reference = CreateDataReference <DataInt>(entity);
Assert.Equal(1, reference.Current().A);
Assert.Equal(1, reference.Current <DataInt>().A);
Assert.Throws <InvalidOperationException>(() => reference.Current <DataEmpty>());
}