How to exclude some files and folders from coverage report?

I am trying to exclude some JS files from coverage report. I have already added this to package.json

"jest": {
    "testPathIgnorePatterns" : ["<rootDir>/node_modules/", "<rootDir>/path/to/dir/" ],
    "testResultsProcessor": "./node_modules/jest-junit-reporter"
  }

Unfortunately files from those dir still appear when I run CI=true npm test -- --coverage

[gaearon]

This is commonly requested & we should support this.

[robcaldecott]

OK, I needed to ignore all *.stories.js files and you can do this by overriding the value for the Jest collectCoverageFrom option, which can be passed on the command-line via a custom npm test command. Note that collectCoverageFrom expects an array so to pass multiple values you specify the option multiple times.

For example:

npm test -- --coverage --collectCoverageFrom=src/**/*.js --collectCoverageFrom=!src/**/*.stories.js

Notice the exclamation point (can I still call it a pling or does that betray my age?) to exclude a pattern.