ruby.git/test/psych/test_stringio.rb, branch v4.0.4 The Ruby Programming Language [ruby/psych] Fix dumping `StringIO` (and potentially others) on Ruby <= 2.7 2025-05-12T16:19:38+00:00 Earlopain 14981592+Earlopain@users.noreply.github.com 2025-05-12T15:51:05+00:00 0c94ae048a277485aa691820277108c2335ec3d3 In Ruby < 3.0, the superclass of StringIO was actually already `Data`, but it doesn't have the expected shape. So, on these earlier versions it errors: > NoMethodError: undefined method `members' for #<StringIO:0x00005641dd5f2880> > vendor/bundle/ruby/2.6.0/gems/psych-5.2.5/lib/psych/visitors/yaml_tree.rb:170:in `visit_Data' This test doesn't fail on 2.7, presumably because it can pull in a newer `stringio` version. https://github.com/ruby/psych/commit/0f40f56268 
In Ruby < 3.0, the superclass of StringIO was actually already `Data`,
but it doesn't have the expected shape. So, on these earlier versions it errors:
> NoMethodError: undefined method `members' for #<StringIO:0x00005641dd5f2880>
>    vendor/bundle/ruby/2.6.0/gems/psych-5.2.5/lib/psych/visitors/yaml_tree.rb:170:in `visit_Data'

This test doesn't fail on 2.7, presumably because it can pull in a newer `stringio` version.

https://github.com/ruby/psych/commit/0f40f56268