Lint/DuplicateMethods false positive when using alias_method to change/change back a method

[tjschuck]

This is something we sometimes do as a test helper method to ensure some sort of behavior out of a method in the class to be tested. Imagine, for example, we wanted save in the tested class to always raise an error when called, but we also don't want it to stay modified:

module FooTest
  def make_save_always_fail
    Foo.class_eval do
      def failed_save
        raise
      end
      alias_method :original_save, :save
      alias_method :save, :failed_save
    end

    yield
  ensure
    Foo.class_eval do
      alias_method :save, :original_save
    end
  end
end

If you call rubocop --only Lint/DuplicateMethods on that snippet, you get a false positive for the "second" definition of save inside the ensure block.

https://wasabigeek.com/blog/practical-metaprogramming-in-ruby-minitest-mock/ outlines a similar form of this.

---

Expected behavior

Should allow multiple alias_method definitions of the same name if they happen in different scopes.

Actual behavior

See above.

Steps to reproduce the problem

See example snippet and command above.

RuboCop version

1.40.0 (using Parser 3.1.3.0, rubocop-ast 1.24.0, running on ruby 3.0.4) [x86_64-darwin21]