public void CouldRemoveFirstAddInTheMiddle()
{
var sd = new SortedDeque <int>();
sd.Add(1);
sd.Add(3);
sd.Add(5);
sd.Add(7);
Assert.AreEqual(sd.First, 1);
Assert.AreEqual(sd.Last, 7);
var fst = sd.RemoveFirst();
Assert.AreEqual(sd.First, 3);
sd.Add(4);
Assert.AreEqual(1, sd.ToList().IndexOf(4));
Assert.AreEqual(2, sd.ToList().IndexOf(5));
Assert.AreEqual(3, sd.ToList().IndexOf(7));
var last = sd.RemoveLast();
sd.Add(8);
Assert.AreEqual(1, sd.ToList().IndexOf(4));
Assert.AreEqual(2, sd.ToList().IndexOf(5));
Assert.AreEqual(3, sd.ToList().IndexOf(8));
sd.Add(6);
Assert.AreEqual(1, sd.ToList().IndexOf(4));
Assert.AreEqual(2, sd.ToList().IndexOf(5));
Assert.AreEqual(3, sd.ToList().IndexOf(6));
Assert.AreEqual(4, sd.ToList().IndexOf(8));
}