public void When_RemoveElement_Expect_Reference(int index) { var vector = new SparseVector <double>(); vector.GetElement(1).Value = 1; vector.GetElement(2).Value = 2; vector.GetElement(3).Value = 3; vector.RemoveElement(index); for (var i = 1; i <= 3; i++) { if (i == index) { Assert.AreEqual(null, vector.FindElement(i)); } else { Assert.AreEqual(i, vector.FindElement(i).Value); } } }