What does parse() return?

I'm not being flippant; ok() expects a boolean. If the method returns something which coerces to a true value, that test assertion will pass.

If you want to continue to use the ok() assertion, make the method return a boolean value in all normal cases.

Update: I posted before I wrote what I really want to write: in the absence of an explicit return, the method will perform an implicit return of the last expression evaluated. Sometimes that's okay, but in this case it's not what you want.