public void PeekTest()
{
Stack stack = new StackBuiltIn();
stack.Push(5);
Assert.AreEqual(5, stack.Peek());
Assert.AreEqual(5, stack.Peek());
stack.Push(7);
Assert.AreEqual(7, stack.Peek());
Assert.AreEqual(7, stack.Peek());
}
public void PopTest()
{
Stack stack = new StackBuiltIn();
stack.Push(5);
Assert.AreEqual(5, stack.Peek());
Assert.AreEqual(5, stack.Pop());
//Assert.IsNull(stack.Peek());
//Assert.IsNull(stack.Pop());
stack.Push(7);
stack.Push(9);
Assert.AreEqual(9, stack.Pop());
Assert.AreEqual(7, stack.Peek());
Assert.AreEqual(7, stack.Pop());
//Assert.IsNull(stack.Pop());
}