Gulpfile.js

var gulp = require("gulp");
var uglify = require("gulp-uglify");
var rename = require("gulp-rename");
var insert = require("gulp-insert");
var eslint = require("gulp-eslint");
var size = require("gulp-size");
var jest = require("gulp-jest").default;

var pjson = require("./package.json");

gulp.task("test", function() {
  return gulp.src("./").pipe(jest());
});

gulp.task("compile", function() {
  return gulp
    .src(["./feature.js"])
    .pipe(eslint())
    .pipe(eslint.format())
    .pipe(eslint.failAfterError())
    .pipe(uglify())
    .pipe(
      insert.prepend(
        "/*! FEATURE.JS " + pjson.version + ", http://featurejs.com */\n"
      )
    )
    .pipe(rename({ extname: ".min.js" }))
    .pipe(size({ showFiles: true }))
    .pipe(size({ showFiles: true, gzip: true }))
    .pipe(gulp.dest("./"));
});

// Build task
gulp.task("build", gulp.parallel("test", "compile"));