ReflectionClassName: accept method calls on local variables

[exterm]

Fix #1179

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.

[exterm]

@koic you're probably pretty busy, but I would love a review on this 😃

[koic]

The ability to call the name method suggests that, similar to has_many :accounts, class_name: Account.name, an offense should be registered:
https://github.com/rubocop/rubocop-rails/pull/1180/files#diff-9d8842c039d0144f6548e139d525048bb9e0651ba63906ca875e35ff52140498R16-R25

[exterm]

I understand the purpose of this cop to be to avoid the use of constant references, which lead to loading all the referenced classes.

Account.name will resolve Account, some_class_in_a_variable.name will not load the class (it will already have been loaded).

I can see how this is kind of an edge case though since it does seem to require the loading of a class (unless the name method here is not Class#name).

I wonder - isn't your concern covered by it 'registers an offense when parameter value is a local variable assigned a constant'?

I can look into this, change this test case to use different variable / method names and add another test case for

expect_offense(<<~RUBY)
  the_class = Account

  has_many :accounts, class_name: the_class.name
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ Use a string value for `class_name`.
RUBY

(Although I think this makes me think that the message shouldn't be "Use a string value for class_name", but rather "Don't use a constant reference for class_name")

[exterm]

OK, I tried it -

  the_class = Account

  has_many :accounts, class_name: the_class.name

does not register an offense even on main. So for now I've just changed the variable and method name in this test. I believe the behavior of the cop is as expected except for the above example which didn't work before either. But it's better to have a false negative than a false positive.

[exterm]

@koic can we merge this? If not, what else is required?