I just came into a Node.js project that has a ton of unit tests, most of which, unfortunately, are outdated and don't run. There's no test runner or any kind of code coverage tool implemented, and it is certainly not in my scope of work to refactor everything.
That being said, that doesn't stop me from wanting to check the code coverage of my work. I've looked at both Istanbul and Blanket and can't find a way to only have them run certain unit tests. Surely, there is a way so that I can get a report that, obviously, reports a very low percentage of coverage, but that I can dive into certain files and such (those that my tests hit) to ensure my code is throughly tested.
With istanbul.js, you can easily get the coverage information this by for example specifying the following command (Following example uses mocha but it will be similar for any test framework):
istanbul cover node_modules/.bin/_mocha -- -u exports -R spec test/test1.spec.js test/test2.spec.js
You can also specify all the tests in particular sub-directory eg: test/yourfeaturetest/*.spec.js. You also have something like test/myfeature/**/*.spec.js to cover all the tests in the test/myfeature directory including tests that could have been created recursively in sub-directories.
As for me, I use gulp and thus utilize plugins such as gulp-istanbul and run tests and coverage via gulp tasks.