cmp different from the string representation

Lisez l’implémentation de cmp dans ext/pathname/pathname.c ainsi que les cas associés dans test/pathname/test_pathname.rb, puis reproduisez les différents résultats de Pathname#<=> et de l’ordre des chaînes décrits dans l’issue. C’est terminé lorsque le comportement de tri attendu est établi et que les tests ou la documentation concernés reflètent clairement cette conclusion.

There's an ordering difference when using the built-in <=> vs the string representation one:

> Pathname.new(File.expand_path('.')).glob('**/*.rb').sort.first(5)
=> [#<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/chain.rb>,
 #<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/error_generator.rb>,
 #<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/expect_chain_chain.rb>,
 #<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/expectation_chain.rb>,
 #<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/message_chains.rb>]
> Pathname.new(File.expand_path('.')).glob('**/*.rb').sort_by(&:to_s).first(5)
=> [#<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks.rb>,
 #<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance.rb>,
 #<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/chain.rb>,
 #<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/error_generator.rb>,
 #<Pathname:/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/expect_chain_chain.rb>]

And the latter corresponds to the classic alternative:

> Dir[File.expand_path('**/*.rb')].sort.first(5)
=> ["/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks.rb",
 "/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance.rb",
 "/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/chain.rb",
 "/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/error_generator.rb",
 "/Users/pirj/source/rspec-dev/repos/rspec-mocks/lib/rspec/mocks/any_instance/expect_chain_chain.rb"]

Just by looking at the cmp implementation and tests I couldn't understand, is this the designed behaviour, or the behaviour is undefined?

Semantically, it would make sense to load rspec/mocks.rb first, and then rspec/mocks/any_instance.rb, not the other way around.
Some discussion in rspec-rails regarding the issues it may cause.
rspec-rails PR to change the helper template to use Pathname#glob instead of Dir.[].

A workaround rspec-rails plans to take is to sort_by(&:to_s) to get back to the string representation-like ordering.

(semi-)Related cops:

• https://docs.rubocop.org/rubocop-rails/cops_rails.html#railsrootpathnamemethods
• https://docs.rubocop.org/rubocop/1.65/cops_lint.html#lintnondeterministicrequireorder