rounded to the smallest value

That means rounded down.

I agree. there was one for 38.53 hours...my solution rounded up to 39 hours, 39 times 0.5 is 19.5, but it 'expected' 19. Doesn't make sense since it tells you to round, and that he drinks 0.5 an hour. I don't think it counts as a coding challenge when the instructions are deliberately not true.

return and the next line of your code must be in the same line for it to work. Your function is returning undefined and that's a falsy value, the tests with test.expect don't check if your function returned a boolean, that's why it seems it works for the ones that expect false.