I'm agree with the black box idea, it's where all the fun is, in a bug resolution.

I've add a test fixture to help people understanding the problem.

What part do you think need to be more detailed ?

There's also 'How I met Your Mother'

Little mistake in the description lyrics :
"99 bottles of beer of the wall" ==> "99 bottles of beer on the wall" in the expected solution after attempt

Probably need to add the second and third implementation in the description, cause we can easily forgot to use them before the Attempt tests remember us that you should use it.