def test_stack_init(self):
stk = Stack()
self.assertEqual(stk.size(), 0)
self.assertEqual(stk.is_empty(), True)
with self.assertRaises(IndexError):
stk.pop()
with self.assertRaises(IndexError):
stk.peek()
def test_stack_pop(self):
stk = Stack()
random_values = get_random_values()
for v in random_values:
stk.push(v)
for v in random_values[::-1]:
stk.pop()
self.assertEqual(stk.is_empty(), True)
with self.assertRaises(IndexError):
stk.pop()
with self.assertRaises(IndexError):
stk.peek()
def test_peeking_at_stack_does_not_remove_item():
stack = Stack()
stack.push(1)
assert_equal(stack.empty(), False)
assert_equal(stack.peek(), 1)
assert_equal(stack.empty(), False)
def test_peeking_at_stack_returns_last_item():
stack = Stack()
stack.push(1)
stack.push(2)
stack.push(3)
assert_equal(stack.peek(), 3)
def test_pushing_to_stack_adds_item_to_stack():
stack = Stack()
assert_equal(stack.empty(), True)
stack.push(1)
assert_equal(stack.empty(), False)
assert_equal(stack.peek(), 1)
def test_stack_peek(self):
stk = Stack()
random_values = get_random_values()
for v in random_values:
stk.push(v)
for v in random_values[::-1]:
self.assertEqual(stk.peek(), v)
stk.pop()
def test_stack_push(self):
stk = Stack()
random_values = get_random_values()
for v in random_values:
stk.push(v)
self.assertEqual(stk.is_empty(), False)
self.assertEqual(stk.peek(), v)
self.assertEqual(stk.pop(), v)
def test_stack_reverse(self):
stk = Stack()
random_values = get_random_values()
for v in random_values:
stk.push(v)
stk.reverse()
for v in random_values:
self.assertEqual(stk.peek(), v)
stk.pop()
class MinStack:
def __init__(self):
self.mins = Stack()
self.items = Stack()
def push(self, item):
min = self.mins.peek()
if min == None or item < min:
self.mins.push(item)
return self.items.push(item)
def pop(self):
item = self.items.pop()
if item == self.mins.peek():
self.mins.pop()
return item
def min(self):
return self.mins.peek()
def test_peeking_at_empty_stack_returns_none():
stack = Stack()
assert_equal(stack.peek(), None)
