The last test:
length = 6 height = 9.1

seems like the result should be false, but the test expects it to be true

There is a problem with the test cases. The last line should use == not ,

answer_book.each { |example| Test.expect(unique(example[:test]) == example[:answer]) }

Last ruby test looks wrong to me.

Your story talks about neighbors (in plural) but the code only deals with one name. Might want to change the story to talk about one person or the requirement to handle multiple names.

I LOVE Ruby

I liked the recursive solution and that you modified the parameter list