gulp.watch - run mocha tests on every file changed

gulpfile.js

// npm i gulp gulp-watch gulp-mocha gulp-batch

var gulp = require('gulp');
var mocha = require('gulp-mocha');
var batch = require('gulp-batch');

gulp.watch(['test/**', 'lib/**'], batch(function (events, cb) {
    return gulp.src(['test/*.js'])
        .pipe(mocha({ reporter: 'list' }))
        .on('error', function (err) {
            console.log(err.stack);
        });
}));