The description specifies that you are to return the index of the firt item for which the block returns true. If you are truely expecting a boolean value returned from the block the test cases should assert that the method returns nil when the block returns a truthy value and not the actualy boolean true value.
The description specifies that you are to return the index of the firt item for which the block returns true. If you are truely expecting a boolean value returned from the block the test cases should assert that the method returns nil when the block returns a truthy value and not the actualy boolean true value.