public void CanSetMultipleFormulas()
{
var mapping = new HbmElement();
IElementMapper mapper = new ElementMapper(typeof(Element), mapping);
mapper.Formulas("formula1", "formula2", "formula3");
Assert.That(mapping.formula, Is.Null);
Assert.That(mapping.Items, Has.Length.EqualTo(3));
Assert.That(
mapping.Items.Cast <HbmFormula>().Select(f => f.Text.Single()),
Is.EquivalentTo(new[] { "formula1", "formula2", "formula3" }));
}