Maybe I'm late, but my tip is to write a lot of comments that describe everything that happens in your code. This way you can reread them after forgetting something.

That can't be, the test is this:

    ([0, 0, 0], 0),
    ([1, 2], 1), # this one

And you can see the expected answer is 1, not 0. Are you sure you're reading the logs ok? The previous test expects 0.