npm ERR! Error: ENOENT, open '<path to project>/node_modules/app/foo/__tests__/bar.spec.js/package.json'

npm test -- SomeTestFileToRun

npm test -- --help

npm test -- Foo

npm test -t ValidationUtil

node_modules/.bin/jest [args]

yarn test src/lib/myfile.test.js

{
...
  "scripts": {
    "test": "jest",
    "testw": "jest --watch",
    "testc": "jest --coverage",
...
  },
  "devDependencies": {
    "jest": "^18.1.0",
    ...
  },

}