def test_peek_when_empty():
# TODO it should raise an exception when peeking an empty queue
q = Queue()
with pytest.raises(InvalidOperationError) as e:
q.peek()
assert str(e.value) == "Method not allowed on empty collection"
pass
def test_enqueue_two():
q = Queue()
q.enqueue("apples")
q.enqueue("bananas")
actual = q.peek()
expected = "apples"
assert actual == expected
def test_peek():
q = Queue()
q.enqueue("apple")
q.enqueue("banana")
q.enqueue("cucumber")
actual = q.peek()
expected = "apple"
assert actual == expected
def test_peek_post_dequeue():
# TODO it should return a new first value if peek is called after a dequeue
q = Queue()
q.enqueue("apples")
q.enqueue("bananas")
q.enqueue("grapes")
q.dequeue()
actual = q.peek()
expected = "bananas"
assert actual == expected
def test_peek(queue_vals):
q = Queue()
assert q.peek() == 'this is an empty Stack'
assert queue_vals.peek() == 8