This change both speeds up specs (less strings to allocate) and helps catch
cases where methods in Discourse are mutating inputs.
Overall we will be migrating everything to use #frozen_string_literal: true
it will take a while, but this is the first and safest move in this direction
This test of `prevent_anons_from_downloading_files` was testing an image instead of an attachment and it was testing the wrong upload URL. I fixed the test, but with `config.public_file_server.enabled = true` on the test environment, this will always fail, as preventing anonymous file downloads depends on nginx. So, I marked the test as skipped, for now.
If for some reason `Discourse.store.path_for` returns `nil`, the
forum would throw an error rather than returning 404.
Why would it be `nil`? One cause could be changing the type of
file store and having the `url` field no longer be relative.
This updates tests to use latest rails 5 practice
and updates ALL dependencies that could be updated
Performance testing shows that performance has not regressed
if anything it is marginally faster now.
