public void Peek_PushTwoItemsAndPop_ReturnsHeadElement()
{
var stack = new MyStack <int>();
stack.Push(1);
stack.Push(2);
stack.Pop();
Assert.AreEqual(1, stack.Peek());
}
public void Pop_EmptyStack_ThrowsException()
{
var stack = new MyStack <int>();
Assert.Throws <InvalidOperationException>(() => { stack.Pop(); });
}