For almost all Ruby developers, Simplecov is synonymous with code coverage. Many other paid services like Coveralls, Codacy etc all repackage Simplecov reports, which are generated in your CI pipeline.
Simplecov shows you a long list of files and their coverage %, but they can't show you if the file is being used or not, or maybe there are merely autoloaded in test times -- In which false +ve test coverage is also counted.
Don't be overwhelmed, OyenCov highlights where you can start first.
Some of the controllers we aren't testing enough.
OyenCov comes to the rescue! We clearly show the classes/modules/methods that are being heavily used but lack test coverages, in clear red/pink/yellow/white rows.
More info on our usage-weighting formula can be found in OyenCov Docs: Score Formula page.
Keep Simplecov, then add OyenCov to your workflow.
Simplecov costs nothing and it has been great. For the Rails projects using OyenCov, it's also required for OyenCov gem to function.
However, we believe many teams can better benefit from a more actionable, useful test coverage metric that OyenCov offers.