def test_placed_by(self):
A = SearchNode('A')
B = SearchNode('B')
stack = SearchStack()
stack.push(A)
stack.push(B, A)
node = stack.pop()
self.assertEquals(stack.placed_by(node.name).name, 'A')
node = stack.pop()
self.assertIsNone(stack.placed_by(node.name))
def test_placed_by(self):
A = SearchNode('A')
B = SearchNode('B')
stack = SearchStack()
stack.push(A)
stack.push(B, A)
node = stack.pop()
self.assertEquals(stack.placed_by(node.name).name, 'A')
node = stack.pop()
self.assertIsNone(stack.placed_by(node.name))
