fails:Range#cover? raises an ArgumentError without exactly one argument
fails:Range#cover? returns true if argument is equal to the first value of the range
fails:Range#cover? returns true if argument is equal to the last value of the range
fails:Range#cover? returns true if argument is less than the last value of the range and greater than the first value
fails:Range#cover? returns true if argument is sole element in the range
fails:Range#cover? returns false if range is empty
fails:Range#cover? returns false if the range does not contain the argument
fails:Range#cover? uses the range element's <=> to make the comparison
fails:Range#cover? uses a continuous inclusion test
