This allows us to control the trusted proxies while deployed in a private network. Normally Rack::Request will trust all private IPs as trusted proxies, which can caue problems if your users are connection on you network via private IP ranges.
Normally in a rails app this is handled by action_dispatch request, but rack_attack is specifically using the Rack::Request object instead.
Each test reloads the trusted_proxies initializer, which in turn will set Rails.application.config.action_dispatch.trusted_proxies to something new. This will leak into the other tests, but the middleware that it is used in has already been loaded for the whole test suite, so it should have no impact.
