function printSummary() {
  const cFilesWithIssues = Object.keys(filesWithIssues).length;
  gutil.log('');
  gutil.log('Test Completed.');
  gutil.log('Files tested:  ', chalk.cyan(filesTested));
  gutil.log(' - with issues:', chalk.yellow(cFilesWithIssues));
  gutil.log('Errors  : ', chalk.red(allErrors.length));
  gutil.log('Warnings: ', chalk.yellow(allWarnings.length));
  if (IS_TRAVIS) {
    let result = {
      summary: {
        filesTested: filesTested,
        filesWithIssues: cFilesWithIssues,
      },
      errors: allErrors,
      warnings: allWarnings,
    };
    result = JSON.stringify(result, null, 2);
    fs.writeFileSync('./test-results.json', result, 'utf8');
  }
}
Prints a summary of the test results