old_contents: const gulp = require('gulp');
  const eslint = require('gulp-eslint');
  const mocha = require('gulp-mocha');
  
  gulp.task('lint', () => {
      return gulp.src(['./*.js'])
          .pipe(eslint())
          .pipe(eslint.format())
          .pipe(eslint.failAfterError());
  });
  
  gulp.task('test', () => {
      return gulp.src(['./test.js'])
          .pipe(mocha());
  });
  
  gulp.task('default', ['test']);
  
new_contents: 'use strict';
  
  const gulp = require('gulp');
  const eslint = require('gulp-eslint');
  const mocha = require('gulp-mocha');
  
  gulp.task('lint', () => {
      return gulp.src(['./*.js'])
          .pipe(eslint())
          .pipe(eslint.format())
          .pipe(eslint.failAfterError());
  });
  
  gulp.task('test', ['lint'], () => {
      return gulp.src(['./test.js'])
          .pipe(mocha());
  });
  
  gulp.task('default', ['test']);
  
subject: Make sure linting is performed