gulpfile.js

const gulp = require('gulp'),
  mocha = require('gulp-mocha'),
  ts = require('gulp-typescript'),
  tsProject = ts.createProject('tsconfig.json'),
  fsExtra = require('fs-extra'),
  runSequence = require('run-sequence'),
  path = require('path'),
  spawn = require('child_process').spawn,
  { join } = require('path');

let glue = suffix => gulp.src(`src/**/*.${suffix}`).pipe(gulp.dest('lib'));

let watch = (suffix, tasks) => {
  tasks = tasks ? tasks : [suffix];
  return gulp.watch(`src/**/*.${suffix}`, tasks);
}

gulp.task('pug', () => glue('pug'));
gulp.task('md', () => glue('md'));
gulp.task('ejs', () => glue('ejs'));

gulp.task('ts', () => {
  let tsResult = tsProject.src()
    .pipe(tsProject());
  return tsResult.js.pipe(gulp.dest('lib'));
});

gulp.task('watch-ts', () => watch('ts'));
gulp.task('watch-pug', () => watch('pug'));
gulp.task('watch-ejs', () => watch('ejs'));
gulp.task('watch-md', () => watch('md'));

gulp.task('unit', ['build'], () => {
  return gulp.src('test/unit/**/*.js', { read: false })
    .pipe(mocha({ require: ['babel-register'] }));
});

gulp.task('it', ['build'], () => {
  return gulp.src(['test/integration/init.js', 'test/integration/**/*-test.js'], { read: false })
    .pipe(mocha({ bail: true, require: ['babel-register'] }))
    .once('end', () => process.exit());
});

gulp.task('clean', (done) => {
  fsExtra.remove('lib', done);
})

gulp.task('build', done => runSequence('clean', ['md', 'ejs', 'pug', 'ts'], done));

gulp.task('dev', ['build', 'watch-md', 'watch-ejs', 'watch-pug', 'watch-ts']);

gulp.task('test', ['unit']);