public void CanSetLength()
{
var hbm = new HbmColumn();
var mapper = new ColumnMapper(hbm, "aColumn");
mapper.Length(50);
hbm.length.Should().Be("50");
mapper.Executing(m => m.Length(0)).Throws <ArgumentOutOfRangeException>();
mapper.Executing(m => m.Length(-1)).Throws <ArgumentOutOfRangeException>();
}