Simplecov Gem with Ruby on Rails

Code coverage is an important metric for any software project. It measures the proportion of code that is exercised by tests, and can help developers identify areas of their codebase that may not be adequately tested. Developers can improve the quality and reliability of their code by making sure that their tests cover enough of the code. In this article, we will look at the simplecov gem, a code coverage tool for Ruby that helps developers measure and report on the coverage of their code. We will also see how simplecov can be used in combination with the RSpec testing framework to measure coverage in a Rails application.

Installing and Configuring simplecov

To use simplecov with RSpec, you will need to add the gem to your Gemfile and then run bundle install. Here is an example of how you might do this:

# Gemfile
gem 'simplecov'

# terminal
bundle install

Next, you will need to require the simplecov library at the top of your spec_helper.rb file, and start the coverage measurement. Here is an example of how you might do this:

# spec/spec_helper.rb

require 'simplecov'
SimpleCov.start

By default, simplecov will measure coverage for all files in your project. You can customize which files are included in the coverage report by using the add_filter method. For example, you might exclude certain directories or files like this:

# spec/spec_helper.rb

SimpleCov.add_filter 'vendor'…