[Fix #8950] Add IgnoredMethods and IgnoredClasses to Lint/NumberConversion

[dvandersluis]

Fixes #8950, to an extent. There are going to inherently be a number of false positives possible from this cop since it applies to basically any receiver of to_i, etc. other than Time and DateTime, which were hardcoded. Since this cop is disabled by default we probably don't have a lot of external coverage here (searching github for Lint/NumberConversion returns a lot of inline disables though!)

Instead, the classes to ignore are now configurable, and IgnoredMethods was added as well (so the rails duration helpers could be allowed in configuration). This of course isn't going to help when assigned to a variable, because those are checked as well:

x = 10.minutes
x.to_i # will be registered

Another potential issue is that Integer(10.minutes) will work but Integer(10.minutes, 10), which is the default suggestion/correction, does not work when the first argument is not a string. Should I change that as well to only add the base if the first arg is a known string?

---

Before submitting the PR make sure the following are checked:

• 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.
• Added an entry to the Changelog if the new code introduces user-observable changes. See changelog entry format.
• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Run bundle exec rake default. It executes all tests and RuboCop for itself, and generates the documentation.

[koic]

I think this approach is fine. For #8950, default.yml of rubocop-rails (or .rubocop.yml of user) can the following settings:

Lint/NumberConversion:
  IgnoredMethods:
    - seconds
    - second
    - hours
    - hour
    (snip)

And the following methods can be added.
https://github.com/rails/rails/blob/v6.0.3.4/activesupport/lib/active_support/core_ext/numeric/time.rb

[koic]

Suggested change

	* [#8950](https://github.com/rubocop-hq/rubocop/pull/8950): Add `IgnoredMethods` and `IgnoredClasses` to `Lint/NumberConversion`. ([@dvandersluis][])
	* [#8950](https://github.com/rubocop-hq/rubocop/issues/8950): Add `IgnoredMethods` and `IgnoredClasses` to `Lint/NumberConversion`. ([@dvandersluis][])

[dvandersluis]

I'll fix this but FYI this is coming from the rake changelog:* tasks. I assume it's done like this because it's impossible to tell whether the reference is an issue or PR, but github redirects pull/xxx to issues/xxx if it's actually an issue so I assume that's why @marcandre did it this way.

[marcandre]

Agree it doesn't actually matter. Still, I'll change the script so it writes issues/nnn when there is [Fix #nnn] in the commit message, and pulls/x if there isn't (assuming that the link will point to the PR to be created). #8963

[dvandersluis]

Oh nice great suggestion @koic, I’ll make a PR to rubocop-rails tomorrow!

[bbatsov]

It'd be nice if we updated the cop description with explanation of its limitations and why we had to disable it by default.

[dvandersluis]

@bbatsov added to the cop description. Should I make it not use a base with Integer() if not given a string?

[bbatsov]

I guess that would miss all cases where the first argument is not a literal, so probably we're better off not doing so, at least for now. Thanks for tackling this!