public void AddPart_AfterBeginEditing_ChangesProportions()
{
// arrange
var soil = new Soil()
{
Soil.Part <Sand>(1), Soil.Part <Turf>(3)
};
// act
soil.EndEdit();
soil.BeginEdit();
soil.Add <Sand>(2);
// assert
Assert.AreEqual(3, soil[SoilParts.Sand]);
Assert.AreEqual(3, soil[SoilParts.Turf]);
}
