Steps to reproduce:

1. Go to a URL like http://test.archiveofourown.org/collections/Third_Monday_13/signups/123353552626 – that is, a URL to view a non-existent sign-up in a very much existent challenge

What happens:

A 404 error.

What should happen:

You should be redirected to the collection with a red flash message: "What sign-up did you want to work on?"

Trick question! Giving a 404 is what it should do. However, we have some unused code from when we thought it should redirect you to the collection with a flash message.

Solution:

We should remove the unused portion of the load_sign_up_from_id method (including the no_signup method itself) in controllers/challenge_signups_controller.rb.

Please also update the pending test in spec/controllers/challenge_signups_controller_spec.rb.