Code coverage "Unknown" using jest 15.1.1

Look at your link very carefully:

collectCoverageFrom: {
  description: wrap(
    'relative to <rootDir> glob pattern matching the files that coverage ' +
      'info needs to be collected from.'
      ...

You can't use <rootDir>. Try:

collectCoverageFrom: [
    "**/app_modules/**",
    "**/src/**"
],