public void Constraints()
{
Assert.Equal(0, _mom.Constraints.Count);
Assert.Equal(0, _child.Constraints.Count);
DataRelation Relation = new DataRelation("Rel", _mom.Columns[1], _child.Columns[0]);
_set.Relations.Add(Relation);
Assert.Equal(1, _mom.Constraints.Count);
Assert.Equal(1, _child.Constraints.Count);
Assert.IsType<ForeignKeyConstraint>(_child.Constraints[0]);
Assert.IsType<UniqueConstraint>(_mom.Constraints[0]);
}