Fix bug for invalid bytes in UTF-8 in Lint/PercentStringArray cop

[pocke]

When RuboCop analyses the following code, RuboCop crashes.

test.rb

%W(\255)

Reproduce

$ rubocop --debug test.rb

Expected behavior

RuboCop doesn't crash.

Actual behavior

got the following error.

For /Users/masataka-kuwabara/ghq/github.com/bbatsov/rubocop: configuration from /Users/masataka-kuwabara/ghq/github.com/bbatsov/rubocop/.rubocop.yml
Inheriting configuration from /Users/masataka-kuwabara/ghq/github.com/bbatsov/rubocop/.rubocop_todo.yml
Default configuration from /Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/config/default.yml
Inheriting configuration from /Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/config/enabled.yml
Inheriting configuration from /Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/config/disabled.yml
Inspecting 1 file
Scanning /Users/masataka-kuwabara/ghq/github.com/bbatsov/rubocop/test.rb
invalid byte sequence in UTF-8
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/lint/percent_string_array.rb:39:in `gsub'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/lint/percent_string_array.rb:39:in `block in contains_quotes_or_commas?'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/lint/percent_string_array.rb:35:in `any?'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/lint/percent_string_array.rb:35:in `contains_quotes_or_commas?'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/lint/percent_string_array.rb:25:in `on_percent_literal'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/mixin/percent_literal.rb:15:in `process'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/lint/percent_string_array.rb:21:in `on_array'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/commissioner.rb:42:in `block (2 levels) in on_array'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/commissioner.rb:97:in `with_cop_error_handling'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/commissioner.rb:41:in `block in on_array'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/commissioner.rb:40:in `each'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/commissioner.rb:40:in `on_array'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/ast_node/traversal.rb:13:in `walk'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/commissioner.rb:59:in `investigate'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/team.rb:121:in `investigate'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/team.rb:109:in `offenses'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cop/team.rb:52:in `inspect_file'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:228:in `inspect_file'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:198:in `block in do_inspection_loop'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:188:in `loop'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:188:in `do_inspection_loop'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:93:in `block in file_offenses'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:103:in `file_offense_cache'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:91:in `file_offenses'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:82:in `process_file'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:59:in `block in inspect_files'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:57:in `each'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:57:in `inspect_files'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/runner.rb:35:in `run'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cli.rb:72:in `execute_runner'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/lib/rubocop/cli.rb:28:in `run'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/bin/rubocop:14:in `block in <top (required)>'
/Users/masataka-kuwabara/.rbenv/versions/2.3.1/lib/ruby/2.3.0/benchmark.rb:308:in `realtime'
/Users/masataka-kuwabara/.gem/ruby/2.3.0/gems/rubocop-0.42.0/bin/rubocop:13:in `<top (required)>'
/Users/masataka-kuwabara/.rbenv/versions/2.3/bin/rubocop:23:in `load'
/Users/masataka-kuwabara/.rbenv/versions/2.3/bin/rubocop:23:in `<main>'
C

Offenses:

test.rb:1:1: C: Style/Encoding: Missing utf-8 encoding comment.
%W(\255)
^^^^^^^^
test.rb:1:1: C: Style/FrozenStringLiteralComment: Missing frozen string literal comment.
%W(\255)
^

1 file inspected, 2 offenses detected
Finished in 0.10227428999860422 seconds

Note

scrub_rb gem is an implementation of String#scrub by pure ruby. String#scrub doesn't exist older than ruby 2.0. So, I've added the gem as a new runtime_dependency.

RuboCop version

current HEAD of master branch.

$ rubocop -V
0.42.0 (using Parser 2.3.1.2, running on ruby 2.3.1 x86_64-darwin15)

---

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).
• Used the same coding conventions as the rest of the project.
• 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.
• All tests are passing.
• The new code doesn't generate RuboCop offenses.
• The PR relates to only one subject with a clear title
  and description in grammatically correct, complete sentences.

[bbatsov]

Do we really need a 3rd party gem for this? In general I try to limit RuboCop's dependencies.

[backus]

Do we really need a 3rd party gem for this? In general I try to limit RuboCop's dependencies.

Note that scrub_rb also introduces a monkey patch

[pocke]

@bbatsov Removed dependency for the gem.
I use encode method instead of the gem. ( https://github.com/bbatsov/rubocop/pull/3425/files#diff-61b7d3d18516b6f71f3c6e8aef4992aaR58 )

And I've added a test case.

[bbatsov]

That's better. Thanks!