codeclimate-duplication

codeclimate-duplication is an engine that wraps flay and supports Ruby, Python, JavaScript, and PHP. You can run it on the command line using the Code Climate CLI or on our hosted analysis platform.

What is duplication?

The duplication engine's algorithm can be surprising, but it's actually very simple. We have a docs page explaining the algorithm.

Installation

1. Install the Code Climate CLI, if you haven't already.
2. Run codeclimate engines:enable duplication. This command installs the engine and enables it in your .codeclimate.yml file.
3. You're ready to analyze! cd into your project's folder and run codeclimate analyze.

Configuring

Languages

By enabling the duplication engine with the Code Climate CLI, all supported languages are configured by default, but we recommend adjusting this configuration to enable only the languages you care about. If you have a project with Ruby and JavaScript files, you might want the following configuration:

engines:
  duplication:
    enabled: true
    config:
      languages:
      - ruby
      - javascript

This will tell the duplication engine to analyze Ruby and JavaScript files.

JavaScript

The engine uses babylon to parse JS source code. Here's a configuration example that enables both flow and jsx:

engines:
  duplication:
    enabled: true
    config:
      languages:
      - javascript
      javascript_plugins:
      - flow
      - jsx

For a full list of Babylon plugins: https://github.com/babel/babylon#plugins

Note: If no config.javascript_plugins is provided, the default includes jsx and objectRestSpread.

Threshold

We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.

The threshold configuration represents the minimum "mass" a code block must have to be analyzed for duplication. If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.

To adjust this setting, add a mass_threshold key with your preferred value for an enabled language:

engines:
  duplication:
    enabled: true
    config:
      languages:
        ruby:
          mass_threshold: 20
        javascript:

Note that you have the update the YAML structure under the languages key to the Hash type to support extra configuration.

Excluding files and directories

As with any other Code Climate engine, you can exclude certain files or directories from being analyzed. For more information, see Exclude paths for specific engines in our documentation.

engines:
  duplication:
    exclude_paths:
    - examples/