public void Empty_stack_after_push_one_element_is_stack_with_one_element()
{
MyStack <int> stack = new MyStack <int>();
stack.Push(123);
Assert.AreEqual(1, stack.Count());
}
public void New_created_stack_have_not_elements()
{
MyStack <int> stack = new MyStack <int>();
Assert.AreEqual(0, stack.Count());
}