Add Capybara/VisibilityMatcher cop

[aried3r]

Fixes #885.

This is a work in progress still, since it's my first cop.

---

Before submitting the PR make sure the following are checked:

• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Added an entry to the changelog if the new code introduces user-observable changes.
• The build (bundle exec rake) passes (be sure to run this locally, since it may produce updated documentation that you will need to commit).

If you have created a new cop:

• Added the new cop to config/default.yml.
• The cop documents examples of good and bad code.
• The tests assert both that bad code is reported and that good code is not reported.

[pirj]

Flawless headstart! 👏

[aried3r]

I believe I have this PR in an acceptable working state except for the node matchers that are not as strict as they could be. But I don't know how to properly write the possible signatures.

[pirj]

Looks great, I have nothing to add!
To me, it's none of this cop's business to check if the first argument is a sym or not, so a flexible pattern is fine.

Can you please resolve the conflict?

@bquorning @Darhazer do you have any objections on onboarding this new cop?

[aried3r]

Can you please resolve the conflict?

Rebased, squashed and resolved.

[bquorning]

Good stuff! Thanks for contributing.

One comment though. Instead of

expect(page).to have_selector('.my_element', count: 1, visible: false, normalize_ws: true)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `:all` or `:hidden` instead of `false`.

I would prefer

expect(page).to have_selector('.my_element', count: 1, visible: false, normalize_ws: true)
                                                       ^^^^^^^^^^^^^^ Use `:all` or `:hidden` instead of `false`.

That is, highlighting only the offending part of the hash argument.

You can do this by having the node matchers return that part of the node by using $, e.g.

(send nil? :have_selector ... (hash <$(pair (sym :visible) true) ...>))

and then using the return value (which is also yielded, if you call the node matcher with a block) – e.g.

visible_true?(node) do |arg|
  add_offense(arg, message: MSG_TRUE)
end

[aried3r]

Good point, I didn't know how to do that, thanks for the pointers. I've added these changes and am now waiting for CI. I will squash if you approve the changes.

[pirj]

Go ahead, looks perfect.

[aried3r]

Done.

[pirj]

Thank you for your contribution!

[bquorning]

🙏 Thank you @aried3r

[aried3r]

Thank you for all the help!