gulpfile.js

const gulp = require('gulp');
// ES6 JS/JSX Lineter -- Check for syntax errors
const eslint = require('gulp-eslint');
// Test Framework
const mocha = require('gulp-mocha');
// Prettifying
const prettier = require('gulp-prettier');

const prettyConf = require('./.prettierrc.json');

const testFolder = 'test';

const allJSFiles = [
  '*.js',
  `${testFolder}/**/*.js`,
  `${testFolder}/*.js`
];

const esLintOpts = { configFile: '.eslintrc.json', fix: true };

// Lint JS/JSX Files (For Express)
gulp.task('lint', () => {
  return gulp
    .src(allJSFiles)
    .pipe(eslint({ configFile: '.eslintrc.json' }))
    .pipe(eslint.format())
    .pipe(eslint.failAfterError());
});

gulp.task('test', () => {
  return gulp.src('test/*.js', { read: false }).pipe(mocha())
    .once('error', () => {
      process.exit(1);
    });
});

gulp.task('fix', () => {
  return gulp.src(allJSFiles).pipe(eslint(esLintOpts))
    .pipe(eslint.format())
    .pipe(eslint.failAfterError())
    .pipe(gulp.dest((file) => {
      return file.base;
    }));
});

gulp.task('pretty', () => {
  return gulp.src(allJSFiles).pipe(prettier(prettyConf))
    .pipe(eslint(esLintOpts))
    .pipe(gulp.dest((file) => {
      return file.base;
    }));
});

gulp.task('default', gulp.series('lint', 'test'));