[Fix #6132] Fix a false negative for Naming/FileName

[koic]

Fixes #6132.

Summary

This PR fixes a false negative for Naming/FileName when Include of AllCops is the default setting.

The important change in this PR is below.

diff --git a/lib/rubocop/cop/naming/file_name.rb
b/lib/rubocop/cop/naming/file_name.rb
index a025a73b7..be3f1c5aa 100644
--- a/lib/rubocop/cop/naming/file_name.rb
+++ b/lib/rubocop/cop/naming/file_name.rb
@@ -32,7 +32,7 @@ module RuboCop

         def investigate(processed_source)
           file_path = processed_source.file_path
-          return if config.file_to_include?(file_path)
+          return if config.file_to_exclude?(file_path)

The problem is that the target to be excluded was Include instead of Exclude.

Also this PR adds the RuboCop::Config#allowed_camel_case_file? method to judge ignoring Gemfile, Rakefile, etc described in Include.

Other Information

This false negative was noticed by adding **/*.rb to config/default.yml at #5882.

https://github.com/rubocop-hq/rubocop/pull/5882/files#diff-e93280b3b31a6438c533a5f3232340d8R18

---

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• 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 rake default or rake parallel. It executes all tests and RuboCop for itself, and generates the documentation.

[rrosenblum]

I think this if statement can be converted to

pattern.to_s =~ /[A-Z]/ &&
  (match_path?(pattern, relative_path) ||
   match_path?(pattern, absolute_path))

That way the else can be eliminated entirely.

Also, what kind of object is pattern? Assuming that pattern is a symbol, to_s is unnecessary because =~ works with symbols.

[koic]

That way the else can be eliminated entirely.

Oh, I see! I fixed the conditional expression simple.

Also, what kind of object is pattern?

If !ruby/regexp /regexp$/ is written in Include of .rubocop.yml, a Regexp instance is returned.
https://github.com/rubocop-hq/rubocop/blob/1bff66b2b8bafd215c106ee06411277d5554581d/spec/rubocop/cli_spec.rb#L996

In that case this code need to_s to prevent TypeError.

[rrosenblum]

If !ruby/regexp /regexp$/ is written in Include of .rubocop.yml, a Regexp instance is returned.

That makes more sense. I wasn't even thinking about pattern being regex. I'm so used to the paradigm of to_s =~ // being used unnecessarily with symbols.