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 queue_vals():
queue = Queue()
queue.enqueue(8)
queue.enqueue('hi')
queue.enqueue(-4)
queue.enqueue(6)
return queue
def test_peek():
q = Queue()
q.enqueue("apple")
q.enqueue("banana")
q.enqueue("cucumber")
actual = q.peek()
expected = "apple"
assert actual == expected
def test_dequeue_when_full():
q = Queue()
q.enqueue("apples")
q.enqueue("bananas")
actual = q.dequeue()
expected = "apples"
assert actual == expected
def test_enqueue_two():
q = Queue()
q.enqueue("apples")
q.enqueue("bananas")
actual = q.peek()
expected = "apples"
assert actual == expected
def test_enqueue(queue_vals):
# no nodes
q = Queue()
assert q.front == None
assert q.rear == None
# only one node
q.enqueue(5)
assert q.front.value == 5
assert q.rear.value == 5
# two nodes
q.enqueue(7)
assert q.front.value == 5
assert q.rear.value == 7
assert queue_vals.rear.value == 6
assert queue_vals.front.value == 8
def test_is_empty(queue_vals):
q = Queue()
assert q.is_empty() == True
assert queue_vals.is_empty() == False
def test_peek(queue_vals):
q = Queue()
assert q.peek() == 'this is an empty Stack'
assert queue_vals.peek() == 8
def test_exhausted():
# TODO TODO is empty should return true after dequeueing all previously queued items
q = Queue()
q.enqueue("apples")
q.enqueue("bananas")
q.enqueue("grapes")
q.dequeue()
q.dequeue()
q.dequeue()
actual = q.is_empty()
expected = True
assert actual == expected
def test_is_empty():
# TODO is empty should return true if no items were enqueued
q = Queue()
actual = q.is_empty()
expected = True
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_enqueue():
q = Queue()
q.enqueue("apple")
actual = q.front.value
expected = "apple"
assert actual == expected