Update to Rails 7

[pablobm]

This description has been updated since the PR was first created. The first few comments in the thread reflect the conversation while trying to find a fix to the issue of lingering constants.

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Administrate was already compatible with Rails 7, but its specs weren't. This PR includes all necessary fixes, including a workaround for a strange Ruby behaviour when undefining constants on Ruby 3.x.

Specifically, spec/generators/dashboard_generator_spec.rb creates a number of classes and then attempts to undefine them, but these appear to linger around, affecting results at spec/generators/routes_generator_spec.rb. From what I can tell, this affects the specs, but not real world usage.

After trying a few things, I ended up with a bit of a hack: in spec/generators/dashboard_generator_spec.rb I define those classes to be children of TestRecord. Then the routes generator explicitly filter those out.

[pablobm]

@nickcharlton - Not sure what to do about this. I'm considering skipping the offending example under Ruby 3.x. Thoughts?

[nickcharlton]

Hmm, interesting. On spec/generators/routes_generator_spec.rb:123, it does pass locally with Ruby 3.2. It looks like the failure is because the routes file contains foos#index but not customers#index, have we made any changes that might make that to be the case?

[pablobm]

The specs do pass individually. The problem is running them all together, particularly when spec/generators/dashboard_generator_spec.rb runs before spec/generators/routes_generator_spec.rb.

1. The first one generates temporary models and dashboards, like Foo and FooDashboard at https://github.com/thoughtbot/administrate/blob/main/spec/generators/dashboard_generator_spec.rb#L28
2. These temporary classes are theoretically cleaned up in ensure blocks at the end of each example: https://github.com/thoughtbot/administrate/blob/main/spec/generators/dashboard_generator_spec.rb#L60
3. However they are still around when the spec for the routes generator runs, and they are returned by ActiveRecord::Base.descendants at https://github.com/thoughtbot/administrate/blob/main/lib/generators/administrate/routes/routes_generator.rb#L74.
4. These "zombie" models make the route generator think that those are models that need routes, creating them when they shouldn't exist.

[nickcharlton]

Oh, right I see! Yeah, I neglected to try not just running them standalone.

Any thoughts on why it might be showing up on 3.1/3.1 only?

[pablobm]

No idea at the moment. I tried running a bisect through Rails's commit history, but there is a large section around 7.0.0.alpha (or something like that) where specs fail for different reasons (bug in Rails at the time, from what I gather). I may give it another whirl this week, but I'm going to timebox it as I don't want to spend too much longer on this.

[pablobm]

I had another look. The other error that I mention appears for the first time with this Rails commit: rails/rails@cb82f5f This is too esoteric for me, but it does sound related to our issue.

I've been playing with it a bit at main...pablobm:administrate:rails70-bisect. I may give it another go, but this is well beyond my expertise.

[pablobm]

I appear to have found a fix for the issue of lingering constants (see PR description), so I have marked the PR as ready to review.

[littleforest]

🎉