Good point, I've added this to the test fixture now, thank you!

Thanks for the comment-I've opted to skip that edge case altogether as this is only a 7 kyu but I'll explicitly state that this case can't happen in the description.

Thanks for the feedback, I'll state that it should be case-insensitive and add a decent test case.

Thanks for your comments, I've updated the method definition and will rule out the 'alphabeta' case in the description to avoid confusion.

Thanks, that is what I get for writing it when tired!
I've revised the description and switched it to use assert_equals, thanks for pointing that out!

This is just too good!

Sadly, that is only true until you work with someone who doesn't follow that convention.

Looks like the tests need to made a bit more stringent!