public void SingleListTest()
{
SingleList <TestEntity> list = new SingleList <TestEntity>();
Assert.AreEqual(0, list.Count);
var link1 = new TestEntity(1);
list.AddFirst(link1);
Assert.AreEqual(1, list.Count);
Assert.AreEqual(link1, list.First);
var link2 = new TestEntity(2);
SingleList <TestEntity> .AddAfter(link1, link2);
Assert.AreEqual(2, list.Count);
var link3 = new TestEntity(2);
SingleList <TestEntity> .AddAfter(link2, link3);
Assert.AreEqual(3, list.Count);
list.RemoveFirst();
Assert.AreEqual(2, list.Count);
Assert.AreEqual(link2, list.First);
SingleList <TestEntity> .RemoveAfter(link2);
Assert.AreEqual(1, list.Count);
list.RemoveFirst();
Assert.AreEqual(0, list.Count);
}