def test_delete(self):
# 17 7 15 15
# / \ / \ / \ / \
# 15 11 --> 15 11 --> 7 11 --> 10 11
# / \ / / \ / \ / \
# 6 10 7 6 10 6 10 6 7
heap = Heap(max_heap())
heap[2].value = 11
heap.delete_root()
self.assertTrue(test_binary_node(heap.root, 15, 10, 11, None))
self.assertTrue(test_binary_node(heap.root.left, 10, 6, 7, 15))
self.assertTrue(test_binary_node(heap.root.right, 11, None, None, 15))
self.assertTrue(test_binary_node(heap.root.left.left, 6, None, None, 10))
self.assertTrue(test_binary_node(heap.root.left.right, 7, None, None, 10))
# 15 7 11
# / \ / \ / \
# 10 11 --> 10 11 --> 10 7
# / \ / /
# 6 7 6 6
heap.delete_root()
self.assertTrue(test_binary_node(heap.root, 11, 10, 7, None))
self.assertTrue(test_binary_node(heap.root.left, 10, 6, None, 11))
self.assertTrue(test_binary_node(heap.root.right, 7, None, None, 11))
self.assertTrue(test_binary_node(heap.root.left.left, 6, None, None, 10))
# 11 6 10
# / \ / \ / \
# 10 7 --> 10 7 --> 6 7
# /
# 6
heap.delete_root()
self.assertTrue(test_binary_node(heap.root, 10, 6, 7, None))
self.assertTrue(test_binary_node(heap.root.left, 6, None, None, 10))
self.assertTrue(test_binary_node(heap.root.right, 7, None, None, 10))
# 10 7
# / \ --> /
# 6 7 6
heap.delete_root()
self.assertTrue(test_binary_node(heap.root, 7, 6, None, None))
self.assertTrue(test_binary_node(heap.root.left, 6, None, None, 7))
# 7
# / --> 6
# 6
heap.delete_root()
self.assertTrue(test_binary_node(heap.root, 6, None, None, None))
# 6 --> None
heap.delete_root()
self.assertFalse(heap.root)
