Codecov vs. Istanbul vs. OpenCppCoverage vs. SimpleCov Comparison Chart

JavaScript test coverage made simple. Istanbul instruments your ES5 and ES2015+ JavaScript code with line counters, so that you can track how well your unit-tests exercise your codebase. The nyc command-line-client for Istanbul works well with most JavaScript testing frameworks, tap, mocha, AVA, etc. First-class support of ES6/ES2015+ using babel-plugin-Istanbul. Support for the most popular JavaScript testing frameworks. Support for instrumenting subprocesses, using the nyc command-line interface. Adding coverage to your mocha tests could not be easier. Now, simply place the command nyc in front of your existing test command. nyc's instrument command can be used to instrument source files outside of the context of your unit tests. nyc is able to show you all Node processes that are spawned when running a test script under it. By default, nyc uses Istanbul's text reporter. However, you may specify an alternative reporter.

SimpleCov is a code coverage analysis tool for Ruby. It uses Ruby's built-in Coverage library to gather code coverage data, but makes processing its results much easier by providing a clean API to filter, group, merge, format, and display those results, giving you a complete code coverage suite that can be set up with just a couple lines of code. SimpleCov/Coverage track covered ruby code, gathering coverage for common templating solutions like erb, slim, and haml is not supported. In most cases, you'll want overall coverage results for your projects, including all types of tests, Cucumber features, etc. SimpleCov automatically takes care of this by caching and merging results when generating reports, so your report actually includes coverage across your test suites and thereby gives you a better picture of blank spots. SimpleCov must be running in the process that you want the code coverage analysis to happen on.