import unittest


class TestPriorityQueue(unittest.TestCase):

    def test_priority_queue(self):
        priority_queue = PriorityQueue()
        self.assertEqual(priority_queue.extract_min(), None)
        priority_queue.insert(PriorityQueueNode('a', 20))
        priority_queue.insert(PriorityQueueNode('b', 5))
        priority_queue.insert(PriorityQueueNode('c', 15))
        priority_queue.insert(PriorityQueueNode('d', 22))
        priority_queue.insert(PriorityQueueNode('e', 40))
        priority_queue.insert(PriorityQueueNode('f', 3))
        priority_queue.decrease_key('f', 2)
        priority_queue.decrease_key('a', 19)
        mins = []
        while priority_queue.array:
            mins.append(priority_queue.extract_min().key)
        self.assertEqual(mins, [2, 5, 15, 19, 22, 40])
        print('Success: test_min_heap')


def main():
    test = TestPriorityQueue()
    test.test_priority_queue()


if __name__ == '__main__':
    main()