public void TestExceptGroupsFindsUniqueElementsInAGroup()
{
var gp1 = new GridPoint(1, 1);
var gp2 = new GridPoint(2, 2);
var gp3 = new GridPoint(3, 3);
var group1 = new Group(gp1, gp2, gp3);
var group2 = new Group(gp2);
var group3 = new Group(gp3);
var newGroup = group1.ExceptGroups(group2, group3);
Assert.AreEqual(1, newGroup.Count);
Assert.IsTrue(newGroup.Contains(gp1));
}
