def METHOD_NAME(self):
    func = makefn(5, {
        5: [3, 4],
        4: [1],
        3: [2],
        2: [1],
        1: [2]
    })
    domtree = DominatorTree(func)
    self.assertEqual({
        1: 5, 2: 5, 3: 5, 4: 5, 5: 5
    }, idom(func, domtree))