I’m using the awesome Simplecov gem to see where I stand with test coverage within my apps.
It’s very simple to use:
(1) install the gem:
gem 'simplecov', require: false, group: :test
(2) include the gem in your test suite (for me that meant at the very top of test/test_helper.rb):
require 'simplecov' SimpleCov.start
(3) run your tests
# for example
bin/rails test
(4) and then, just open the .index html file in /coverage