Rubocop Markdown

Run Rubocop against your Markdown files to make sure that code examples follow style guidelines and have valid syntax.

• Analyzes code blocks within Markdown files
• Shows correct line numbers in output
• Preserves specified language (i.e., do not try to analyze "```sh")
• Supports autocorrect 📝

This project was developed to keep test-prof guides consistent with Ruby style guide back in 2017. Since then, many popular Ruby projects adopted it, including:

• Ruby on Rails
• AnyCable
• ViewComponent
• Action Policy

Add this line to your application's Gemfile:

gem "rubocop-md"

And then execute:

$ bundle install

Or install it yourself as:

$ gem install rubocop-md

Just require rubocop-md in your command:

rubocop -r "rubocop-md" ./lib

Autocorrect works too:

rubocop -r "rubocop-md" -a ./lib

Code in the documentation does not make sense to be checked for some style guidelines (eg Style/FrozenStringLiteralComment).

We described such rules in the default config, but if you use the same settings in your project’s .rubocop.yml file, RuboCop will override them.

Fortunately, RuboCop supports directory-level configuration and we can do the next trick.

At first, add rubocop-md to your main .rubocop.yml:

# .rubocop.yml

require:
  - "rubocop-md"

Notice: additional options

# .rubocop.yml

Markdown:
  # Whether to run RuboCop against non-valid snippets
  WarnInvalid: true
  # Whether to lint codeblocks without code attributes
  Autodetect: true

Secondly, create empty .rubocop.yml in your docs directory.

├── docs
│   ├── .rubocop.yml
│   ├── doc1.md
│   ├── doc2.md
│   └── doc3.md
├── lib
├── .rubocop.yml # main
└── ...

Third, just run

$ rubocop

Also you can add special rules in the second .rubocop.yml

# rubocop.yml in docs folder

Metrics/LineLength:
  Max: 100

Lint/Void:
  Exclude:
    - '*.md'

You can use this tricks

# my_post.md

... some markdown ...

<span style="display:none;"># rubocop:disable all</span>

```ruby
def my_poor_method(foo)
  [:a, :b, :c] + ["#{foo}".to_sym]
end
```

end of snippet

<span style="display:none;"># rubocop:enable all</span>

... continuation of article ...

• Preprocess Markdown source into Ruby source preserving line numbers
• Let RuboCop do its job
• Restore Markdown from preprocessed Ruby if it has been autocorrected

• RuboCop cache is disabled for Markdown files (because cache knows nothing about preprocessing)
• Uses naive Regexp-based approach to extract code blocks from Markdown, support only backticks-style code blocks*
• No language detection included; if you do not specify language for your code blocks, you'd better turn WarnInvalid off (see above)

* It should be easy to integrate a real parser (e.g. Kramdown) and handle all possible syntax. Feel free to open an issue or pull request!

After checking out the repo, run bundle install to install dependencies. Then, run rake test to run the tests.

To install this gem onto your local machine, run bundle exec rake install.

Bug reports and pull requests are welcome on GitHub at https://github.com/rubocop/rubocop-md.

The gem is available as open source under the terms of the MIT License.