istanbul-baseline
npm install istanbul-baseline
Istanbul reports coverage for all the files your test suit actually loads. But what about the files that are never loaded? They're omitted completely. This skews your coverage stats, and may allow un-tested code to go completely un-noticed.
istanbul-baseline can create a "zero-coverage" report for any set of
files in your project.
node_modules/.bin/istanbul-baseline **/*.js
Then just run your regular coverage/test run. For example:
istanbul cover --report json --print none _mocha ./tests/
And the final report and coverage-check will include all files from the baseline and the main coverage run. And check-coverage
istanbul report html text-summary
istanbul check-coverage --lines 90