def test_save_document_with_root_node():
'''Save a document with a root node.'''
document = Document()
node = Node('root')
document.add(node)
document.save()
assert node.node_id == 1
assert node.parent_id is None
def test_save_document_with_child_node():
'''Save a document with a child node.'''
document = Document()
root = Node('root')
child = Node('child', parent=root)
document.add(root)
document.save()
assert root.parent is None
assert child.parent is root
assert root.node_id == 1
assert child.node_id == 2
assert root.parent_id is None
assert child.parent_id == root.node_id
def test_remove_subtree_from_document():
'''Remove a subtree from the document.'''
document = Document()
root = Node('root')
node = Node('node')
root.children.append(node)
document.add(root)
document.save()
assert root in document.roots
assert node in root.children
document.remove(root)
document.save()
assert root not in document.roots
assert node in root.children