Code Coverage Tools For Padrino

Tags: padrino, ruby

This article is part of an ongoing series about my exploration of the Padrino web framework. If you want to read more about it please check out You sniff around in the sources of the book under GitHub.

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As long as your application exists, some developers leave others will join. It's good to have some metrics about certain code smells. A code smell is part of your source code which may be the root of a design problem but is not actually a bug. It's good to have some tools to be "lord of the smells" for Padrino - don't let smells lower the quality of your project.

(Note: This post is tested with padrino 0.12.2, simplecov 0.9, metric_fu 4.11.1, and ruby 2.1.2p95)

Available Tools

I will go through the following tools and will explain how you can use them.

  • simplecov: It will automatically detect the tests you are using Rubies 1.9's built-in Coverage library to gather code coverage data.
  • metric_fu: Creates churn, code smells, and other coverage tools that generate reports about your code.
  • Online tool for measuring quality and security for your application.


Add the gem to your Gemfile:

gem 'simplecov'

Next, I want to start the code coverage generation every time I run the tests. So we need to add the following line to the spec_helper.rb:

require 'simplecov'

And that's all. Next time when you run the tests you can detect lines with the following output:

Coverage report generated for RSpec to ~/git/job-vacancy/coverage. 209 / 252 LOC (82.94%) covered.

After all tests have been passed, you can see the output in the coverage/index.html file:

Simplecover overview without any special configuration

Simplecover overview without any special configuration

Simplecov with an detailed view

Clicking on a single class will give you a brief overview which lines are not tested

It is also possible to divide parts of your application into several groups. Add options to the Simplecov.start block:

SimpleCov.start do
  add_group "Models", "app/models"
  add_group "Controllers", "app/controllers"
  add_group "Helpers", "app/helpers"
  add_group "Mailers", "app/mailers"

Simplecov grouped output

Simplecov - a more structured view of different components


Add the following line to your Gemfile:

gem 'metric_fu'

When this is done you need to start the metric_fu command from your commandline:

$ ~/git/job-vacancy: metric_fu
******* STARTING METRIC reek
******* ENDING METRIC reek
******* STARTING METRIC flog
******* ENDING METRIC flog
******* STARTING METRIC flay
******* ENDING METRIC flay
******* STARTING METRIC saikuro
******* ENDING METRIC saikuro
******* STARTING METRIC roodi
******* ENDING METRIC roodi
******* STARTING METRIC cane
******* ENDING METRIC cane
******* STARTING METRIC churn
******* ENDING METRIC churn
******* STARTING METRIC stats
******* ENDING METRIC stats
******* STARTING METRIC hotspots
******* ENDING METRIC hotspots
*****Generating graphs
*****Generating graphs for tmp/metric_fu/_data/20140318.yml
all done

It will generate a tmp/metric_fu directory with the following contents:

├── _data
│   └── 20140318.yml
├── output
│   ├── app_app.rb.html
│   ├── app_controllers_page.rb.html
│   ├── app_controllers_sessions.rb.html
│   ├── app_controllers_users.rb.html
│   ├── app_helpers_page_helper.rb.html
│   ├── app_helpers_sessions_helper.rb.html
│   ├── app_helpers_users_helper.rb.html
│   ├── app_mailers_confirmation.rb.html
│   ├── app_mailers_registration.rb.html
│   ├── app_models_job_offer.rb.html
│   ├── app_models_user_observer.rb.html
│   ├── app_models_user.rb.html
│   ├── app_views_application.erb.html
│   ├── app_views_users_edit.erb.html
│   ├── app_views_users_new.erb.html
│   ├── bluff-min.js
│   ├── cane.html
│   ├── cane.js
│   ├── churn.html
│   ├── excanvas.js
│   ├── flay.html
│   ├── flay.js
│   ├── flog.html
│   ├── flog.js
│   ├── Gemfile.html
│   ├── Gemfile.lock.html
│   ├── hotspots.html
│   ├── index.html
│   ├── js-class.js
│   ├── lib_tasks_auth_token_attribute.rake.html
│   ├── reek.html
│   ├── reek.js
│   ├── roodi.html
│   ├── roodi.js
│   ├── saikuro.html
│   ├── spec_app_controllers_users_controller_spec.rb.html
│   ├── stats.html
│   └── stats.js
├── report.yml
└── scratch
    └── churn
        └── 873660ae5973b77b09c47d1dcf03577222095d6e.json

4 directories, 41 files

The following metrics are created by

cane can be used if code quality thresholds are met.

Cane metric to measure code quality thresholds.

churn measures the change ratio of files and you can use this indicator to have more code review, refactoring, more tests for this beast of a file.

Churn measures the change ratio of files

flog a high flog score is an indicator for code complexity.

Flog measures the complexity of a file by giving several flaws in the code a certain ranking.

flay analyzes code similarities in your code base - good way to stay clean with DRY.

Flay measures code duplication.

reek checks your classes and modules after code smells. Under the reek wiki you can find all code smells and what they actually mean.

Check your classes, and modules after code smells.

hotspot a gathering of the flog, flay and reek score of the files in your application.

Hotspot measure overview.

Hotspot measure detailed.

roodi scans your code and informs you about design issues you may have.

Roodi detect issues with your design.

saikuro generates a list of cyclomatic complexity of each method found in your application.

Sailuro meases the cyclomatic complexity of all methods in your application.

Code Climate

Go to the website and register. Once you are logged, you can add any ruby related open source project for free.

Code Climate - add a repository.

It will take a while till the metrics are generated for your application:

Refreshing the metrics takes a while on Code Climate

But when it's ready, you get a nice overview:

Code Climate overview

Or a more detailed overview of single classes:

Detailed information about a single file in Code Climate

Detailed information about a single file in Code Climate

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Hierarchy: previous post