Add Rails/SpecificActionNames cop

[r7kamura]

DHH says that only default CRUD action names should be used and any other action would lead to the creation of a dedicated controller (which itself only has default CRUD actions):

• https://fullstackradio.com/32
• http://jeromedalbert.com/how-dhh-organizes-his-rails-controllers/

And in fact, I think rubocop-rails somewhat expects these default action names to be used in its Rails/ActionOrder cop.

rubocop-rails/config/default.yml

Lines 105 to 112 in f913bb5

	ExpectedOrder:
	- index
	- show
	- new
	- edit
	- create
	- update
	- destroy

With this background in mind,, I think it would be nice to have such a cop available.

---

Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.
• If this is a new cop, consider making a corresponding update to the Rails Style Guide.

[koic]

If the background of this PR description is written, the intention will be conveyed to users.

[koic]

RestfulActionName , or something like that might be more expressive.

[r7kamura]

Hmm. I'd like to discuss the name some more. This is a topic that will be relevant to the detailed description I will write in the Cop comments.

I am considering the following three or more candidates for the name of this Cop:

1. RestfulActionName
2. SpecificActionName
3. ActionName

The original background and motivation is that I want to use only the default action names for CRUD, but what this Cop is actually doing is just limiting the action names to specific predefined name set.

For example, if a convention emerged that there should be one controller class per endpoint, we could do that by limiting all action names to #call or something. Like this, the usage of this Cop is not necessarily limited to RESTful action names. This is why I gave it the rather generic name "ActionName."

If we believe that Cop name should be in keeping with the original good practice or idea, then "Restful" (or "Default" ?) is a good name to use. Otherwise, if we are naming Cop with a focus on what it actually does, we would avoid "Restful" in this case.

If "ActionName" seems too generic, then I would suggest changing the name to something like "SpecificActionName" or "PredefinedActionName".

[andyw8]

I like the concept of this, but it's a tricky to decide what to call it.

I think we should avoid having Name as part of the cop name. This isn't really about how you name the methods, it's about how you structure the app.

My suggestion is Rails/ConstrictedActions.

[koic]

The next release is a bugfix anyway. Let's take a moment to think of a more better name.

[r7kamura]

Thank you for the comments about the cop naming.

I think Rails/ActionName is a bit too abstract and would be better to be at least more concrete. In that sense, I agree with the direction of Rails/ConstrictedActions. For now, I have chosen the Cop name Rails/SpecificActionNames, after the vocabulary of the offense message.

I don't think we should not force the RESTful concept too strongly on users, considering the users who use this simply to reduce the variety of method names. It is difficult to nuance that, but it would be nice for the Cop to say something like "The default is RESTful oriented and we think it should be so if possible, but it is not mandatory".

[koic]

It might be better to be a little more specific about "specific".

[andyw8]

Perhaps the message should include the list of configured actions, e.g.:

Use only specific action names: index, create, show...

[koic]

Note, It may be first how the discussion of rubocop/rails-style-guide#290 will be reflected in the style guide.