def test_stack_push_pop_with_elements(self):
stack = Stack()
stack.push(1)
stack.push(2)
stack.push(5)
assert stack.pop() == 5
assert stack.pop() == 2
assert stack.pop() == 1
def test_pop_decreases_the_stack_size():
stack = Stack()
stack.push(42)
previous_size = stack.size
stack.pop()
assert stack.size == (previous_size - 1)
def test_is_empty(self):
stack = Stack()
assert stack.is_empty() is True
stack.push(1)
assert stack.is_empty() is False
stack.pop()
assert stack.is_empty() is True
def test_size(self):
stack = Stack()
assert len(stack) == 0
stack.push(1)
assert len(stack) == 1
stack.pop()
assert len(stack) == 0
def test_pop_items_with_initial_stack(self):
tests = [1, '0', Stack, lambda x: x, {}, [], None]
stack = Stack(tests)
assert len(stack) == len(tests)
for _ in tests:
stack.pop()
assert stack.is_empty() is True
def test_pop_items(self):
stack = Stack()
with self.assertRaises(StackPopException):
stack.pop()
one = 1
two = 2
stack.push(one)
stack.push(two)
assert len(stack) == 2
assert stack.pop() == two
assert stack.pop() == one
assert len(stack) == 0
def test_pop_on_empty_stack_returns_none():
stack = Stack()
assert stack.pop() == None
def test_pop_returns_the_latest_element_pushed():
stack = Stack()
stack.push("First")
stack.push(42)
assert stack.pop() == 42
