fails:Enumerable#slice_before when given an argument and no block calls === on the argument to determine when to yield
fails:Enumerable#slice_before when given an argument and no block doesn't yield an empty array if the filter matches the first entry or the last entry
fails:Enumerable#slice_before when given an argument and no block uses standard boolean as a test
fails:Enumerable#slice_before when given a block and no argument calls the block to determine when to yield
fails:Enumerable#slice_before when given a block and an argument calls the block with a copy of that argument
