def breadthfirst(self):
"""Generate a breadth-first iteration of the positions of the tree."""
if not self.is_empty():
fringe = LinkedQueue()
fringe.enqueue(self.root())
while not fringe.is_empty():
p = fringe.dequeue()
yield p
for c in self.children(p):
fringe.enqueue(c)
def test_dequeue_returns_and_removes_first_element_from_queue(self):
q = LinkedQueue()
second_element = LinkedQueue._Node('bar', None)
first_element = LinkedQueue._Node('foo', second_element)
q._head = first_element
q._tail = second_element
q._size = 2
expected_result = 'foo'
result = q.dequeue()
self.assertEqual(q._size, 1)
self.assertEqual(result, expected_result)
self.assertIsNot(q._head, first_element)