Add priority queue challenge

arrays_strings/priority_queue/test_priority_queue.py

@@ -0,0 +1,30 @@
+from nose.tools import assert_equal
+
+
+class TestPriorityQueue(object):
+
+    def test_priority_queue(self):
+        priority_queue = PriorityQueue()
+        assert_equal(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)
+        assert_equal(mins, [2, 5, 15, 19, 22, 40])
+        print('Success: test_min_heap')
+
+
+def main():
+    test = TestPriorityQueue()
+    test.test_priority_queue()
+
+
+if __name__ == '__main__':
+    main()