[#494] Create (or use) a Rubocop for the inverse keyword needed in the associations

[Goose97]

• Close Create (or use) a Rubocop for the inverse keyword needed in the associations #494

What happened 👀

Implement custom cop to enforce explicit inverse_of when specifying Rails association
Compass rule

Insight 📝

• Detect Rails model files and only run this cop on such files
• Run test on custom cops during CI (I think we should do it on another ticket)

There are severals trade-offs that I made to reduce the complexity of the cop:

• We can improve the performance by only scanning the top level expressions of the class. I haven't tested it yet, but I suspect that the gain would be negligible. The reason is that we use a lot of different cop rules so that there's a good chance that we have to scan the whole file anyway.
• There's no easy way to distinguish between Rails association helpers and our application functions. If the names collide, it might lead to false positive. However, in practice, we should avoid from naming our methods this way, so I think we could safely ignore this case.

class Author < ActiveRecord::Model
  has_many :books # we should scan this one
  belongs_to :user # and this one

  def test
    SomeModule.has_many(...) # but not this one
  end
end

Note

I encounter a weird bug that prevents me from copying the custom cops to lib/ folder. That's why I have to keep it in the root folder. For more information, see this

Proof Of Work 📹

Screen-Recording-2024-01-03-at-11.59.47.mp4

[Goose97]

@malparty Now think about it, I think we better off splitting the custom cops into a separate repo 🤔 . It's likely that we gonna have more custom cops coming in the future and also makes it easier for current project to adopt the new cops. What do you think?

[malparty]

Thanks for the clear insights about the arbitrations made. That seems fair enough to me 💡

Approved ahead with a question/suggestion 👍

[malparty]

I'm not sure if that works, but can we try to rename the folder: ./rubocop/cops/. At first glance, custom_cops might be hard to recognize for people new in the world of Rails 🛤️

[Goose97]

Agree. Fixed in fba261b

[sanG-github]

What a delightful change!! 🎉