example, how to create separate gulp tasks for compilling main or e2e-test typescript sources to javascript

build.js

// contains just a gulp task that compiles main application TypeScript code to Javascript 
var paths = require('../paths');
var typeScript = require('../typeScript.js');

gulp.task('build-typescript', function() {
  // exclude test typescript sources from paths defined in tsconfig.json
  return typeScript.builder({}, paths.output, [], paths.testTsSourceFilesGlob);
});

e2e.js

// contains just a gulp task that compiles e2e-test TypeScript code to Javascript 
var paths = require('../paths');
var typeScript = require('../typeScript.js');

gulp.task('build-e2e', function() {
  const extraIncludeTsSourceFilesGlobs = [paths.e2eSpecsSrc];
  const excludeTsSourceFilesGlobs = [
    paths.source, // e2e tests don't use application main sources
    paths.unitTestsSrc, // e2e tests don't use unit test sources
    "./typings/jquery/jquery.d.ts", // <-------------- excluding this file, because it declares var $ just like aurelia-protractor, that is used for testing
  ];
  const tsconfigJsonSettingsOverride = {
    module: 'commonjs'
  };
  return typeScript.builder(tsconfigJsonSettingsOverride, paths.e2eSpecsDist, extraIncludeTsSourceFilesGlobs, excludeTsSourceFilesGlobs);
});

paths.js

// contains constants for directories and file globs
var appRoot = 'src/';
var outputRoot = 'dist/';

module.exports = {
  source: appRoot + '**/*.ts',
  output: outputRoot,
  e2eSpecsSrc: 'test/e2e/src/*.ts',
  unitTestsSrc: 'test/unit/**/*.ts',
  testTsSourceFilesGlob: [
    "./test/**/*.ts",
    "./typings/angular-protractor/angular-protractor.d.ts",
    "./typings/aurelia-protractor.d.ts",
  ]
}

tsconfig.json

{
  "version": "1.7.3",
  "compileOnSave": false,
  "compilerOptions": {
    "rootDir": "src/",
    "sourceMap": true,
    "target": "es5",
    "module": "amd",
    "moduleResolution": "classic",
    "declaration": false,
    "noImplicitAny": false,
    "noResolve": true,
    "removeComments": true,
    "noLib": false,
    "noEmitOnError": true,
    "newLine": "LF",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true
  },
  "filesGlob": [
    "./src/**/*.ts",
    "./test/**/*.ts",
    "./typings/**/*.d.ts",
    "./jspm_packages/**/*.d.ts"
  ],
  "exclude": [
    "node_modules"
  ],
  "atom": {
    "rewriteTsconfig": false
  }
}

typeScript.js

// this file contains helper functions to be used by Gulp tasks that compile TypeScript to javascript
const gulp = require('gulp');
const plumber = require('gulp-plumber');
const sourcemaps = require('gulp-sourcemaps');
const extend = require('extend');

const typescript = require('gulp-typescript');
const tsc = require('typescript');

const tsconfig = require('../tsconfig.json');

function createProject(tsconfigJsonSettingsOverride) {
  const gulpTsDefaultSettings = {
    typescript: tsc
  };
  const tsconfigSettings = extend(false, {}, gulpTsDefaultSettings, tsconfigJsonSettingsOverride);
  return typescript.createProject('./tsconfig.json', tsconfigSettings);
}

function builder(tsconfigJsonSettingsOverride, outputPath, extraIncludeTsSourceFilesGlobs, excludeTsSourceFilesGlobs) {
  const tsProject = createProject(tsconfigJsonSettingsOverride);
  const mainTsSourceFilesGlob = clone(tsconfig.filesGlob).concat(extraIncludeTsSourceFilesGlobs);
  excludeTsSourceFilesGlobs.forEach((globElem, index, array) => {
    mainTsSourceFilesGlob.push('!' + globElem);
  });
  return gulp.src(tsconfig.filesGlob.concat(mainTsSourceFilesGlob))
  .pipe(plumber())
  .pipe(sourcemaps.init({loadMaps: true}))
  .pipe(typescript(tsProject))
  .pipe(sourcemaps.write({includeContent: true}))
  .pipe(gulp.dest(outputPath));
}

function clone(o) {
   return JSON.parse(JSON.stringify(o));
}

module.exports = {
  "createProject": createProject,
  "builder": builder,
};