Remove unnecessary routing assertions require

[eugeneius]

ActionDispatch::Assertions has an autoload defined: https://github.com/rails/rails/blob/v7.1.3/actionpack/lib/action_dispatch.rb#L130

That file requires action_dispatch/testing/assertions/routing.rb:
https://github.com/rails/rails/blob/v7.1.3/actionpack/lib/action_dispatch/testing/assertions.rb#L5

So ActionDispatch::Assertions::RoutingAssertions can be referenced without being explicitly required.

rspec/rails/example/controller_example_group.rb, which is loaded before this file, already references it and triggers the autoload, which means this require never has any effect:
https://github.com/rspec/rspec-rails/blob/v6.1.1/lib/rspec/rails/example/controller_example_group.rb#L5

Requiring action_dispatch/testing/assertions/routing.rb on its own doesn't actually work, because it autoloads ActionDispatch::Assertions which then fails to find ActionDispatch::Assertions::RoutingAssertions since it hasn't been defined yet:

$ ruby -r action_dispatch -e "p ActionDispatch::Assertions::RoutingAssertions"
ActionDispatch::Assertions::RoutingAssertions

$ ruby -r action_dispatch -r action_dispatch/testing/assertions/routing -e "p ActionDispatch::Assertions::RoutingAssertions"
/Users/eugene/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/actionpack-7.1.3/lib/action_dispatch/testing/assertions.rb:12:in `<module:Assertions>': uninitialized constant ActionDispatch::Assertions::RoutingAssertions (NameError)

(This is a prerequisite to a larger change, but I wanted to propose it first since it requires a fair bit of explanation.)

[pirj]

Nice, I see something bigger is coming.

Can you please confirm that Rails 6.1 would autoload it the same way, @eugeneius ? The current version of rspec-rails supports Rails 6.1 and 7.x.

[eugeneius]

Yep, the autoload was there already in 6.1.0: https://github.com/rails/rails/blob/v6.1.0/actionpack/lib/action_dispatch.rb#L101