# Test Coverage

Code \(or test\) coverage is a report that shows which parts of the code have been run in some automated tests, making it useful to find untested parts of a codebase.

Tools for generating coverage reports include:

* [Istanbul](https://istanbul.js.org/)
* many test libraries like [Jest](https://facebook.github.io/jest/) have

  built-in support to generate test coverage reports

## References

* [Test Coverage - Martin Fowler](https://www.martinfowler.com/bliki/TestCoverage.html)

