Try out Mutant (mutation testing tool)

[dentarg]

From (now resolved) comment thread at #129 (comment)

I wonder if it's possible to construct a spec that tests this. I tried commenting out the line, all specs still pass.

Hehe, funny that we just (or soon) watched Ruby Tapas episodes about Mutant. :-)

I was thinking, when watching it, that we should try it out here. :-)