title: Typescript Compiler doesn't find several npm packages (gulp-typescript)
body: <p>I'm using gulp-typescript to compile my typescript files. It works but <strong>it doesn't find external modules like "@angular/core"</strong>. How can I configure TSC to look for these modules in node_modules?</p>
  
  <p>PS: I'd like to bundle the typescript files with systemJS. Maybe I can somehow include the systemjs-config so that TSC knows where too look?</p>
  
  <p><strong>CODE:</strong></p>
  
  <pre><code>gulp.task('tsc:release_dist', function() {
      return gulp.src(releaseBuildDest+'/**/*.ts')
          .pipe(gulpIgnore('node_modules/**'))
          .pipe(debug())
          .pipe(tsc({
              noImplicitAny: true,
              out: 'bundle.js',
              module: 'system'
          }))
          .pipe(gulp.dest(releaseBuildDest));
  });
  </code></pre>
  
  <p><strong>my project structure:</strong></p>
  
  <pre><code>.dist/
  ..../release/
  ......./app/ (angular2 components, ...)
  ......./assets/ (css, img, ...)
  ......./node_modules/ (angular2 and other dependencies)
  .......index.html
  .......main.ts
  .......systemjs.config.js
  </code></pre>
  
  <p><strong>console output</strong></p>
  
  <pre><code>[12:25:59] Using gulpfile C:\Develop\frontend\gulpfile.js
  [12:25:59] Starting 'tsc:release_dist'...
  [12:26:00] gulp-debug: dist\release\main.ts
  [12:26:03] gulp-debug: dist\release\app\app.component.spec.ts
  [12:26:05] gulp-debug: dist\release\app\app.component.ts
  [12:26:05] gulp-debug: dist\release\app\app.module.ts
  [12:26:05] gulp-debug: dist\release\app\components\afafc\authafafc\authafafc.component.ts
  [12:26:05] gulp-debug: dist\release\app\components\afafc\langafafc\langafafc.component.ts
  [12:26:06] gulp-debug: 6 items
  dist\release\app\app.component.spec.ts(3,50): error TS2307: Cannot find module '@angular/core/testing'.
  dist\release\app\app.component.spec.ts(4,20): error TS2307: Cannot find module '@angular/platform-browser'.
  dist\release\app\app.component.spec.ts(5,30): error TS2307: Cannot find module '@angular/core'.
  dist\release\app\app.component.ts(1,27): error TS2307: Cannot find module '@angular/core'.
  dist\release\app\app.module.ts(2,31): error TS2307: Cannot find module '@angular/platform-browser'.
  dist\release\app\components\afafc\authafafc\authafafc.component.ts(1,34): error TS2307: Cannot find module '@angular/core'.
  dist\release\app\components\afafc\langafafc\langafafc.component.ts(1,34): error TS2307: Cannot find module '@angular/core'.
  dist\release\main.ts(1,40): error TS2307: Cannot find module '@angular/platform-browser-dynamic'.
  </code></pre>
  
  <p><strong>how my components are requiring these packages:</strong></p>
  
  <pre><code>import { NgModule } from '@angular/core';
  </code></pre>
  
  <p><strong>tsconfig.js</strong></p>
  
  <pre><code>{
    "compilerOptions": {
      "target": "es5",
      "module": "commonjs",
      "moduleResolution": "node",
      "sourceMap": true,
      "emitDecoratorMetadata": true,
      "experimentalDecorators": true,
      "lib": [ "es2015", "dom" ],
      "noImplicitAny": true,
      "suppressImplicitAnyIndexErrors": true
    }
  }
  </code></pre>
  
  <p><strong>Additional information:</strong>
  Everything works fine when I compile the regular dev build using "npm start" which is a shortcut to tsc -p src/. But I'm trying to build a "release build" gulp-task with bundled files. But If I copy everying to my release build directory and try to compile with tsc I get these errors shown above.</p>
  
  <p><strong>package json</strong></p>
  
  <pre><code>{
    "name": "my-project",
    "version": "1.0.0",
    "description": "my-project",
    "scripts": {
      "build": "tsc -p src/",
      "build:watch": "tsc -p src/ -w",
      "build:e2e": "tsc -p e2e/",
      "build:release": "gulp build:release",
      "serve": "lite-server -c=bs-config.json",
      "serve:e2e": "lite-server -c=bs-config.e2e.json",
      "prestart": "npm run build",
      "start": "concurrently \"npm run build:watch\" \"gulp default:watch\" \"npm run serve\"",
      "pree2e": "npm run build:e2e",
      "e2e": "concurrently \"npm run serve:e2e\" \"npm run protractor\" --kill-others --success first",
      "preprotractor": "webdriver-manager update",
      "protractor": "protractor protractor.config.js",
      "pretest": "npm run build",
      "test": "concurrently \"npm run build:watch\" \"karma start karma.conf.js\"",
      "pretest:once": "npm run build",
      "test:once": "karma start karma.conf.js --single-run",
      "lint": "tslint ./src/**/*.ts -t verbose",
      "gulp": "gulp"
    },
    "keywords": [],
    "author": "",
    "license": "UNLICENSED",
    "dependencies": {
      "@angular/common": "~2.4.0",
      "@angular/compiler": "~2.4.0",
      "@angular/core": "~2.4.0",
      "@angular/forms": "~2.4.0",
      "@angular/http": "~2.4.0",
      "@angular/platform-browser": "~2.4.0",
      "@angular/platform-browser-dynamic": "~2.4.0",
      "@angular/router": "~3.4.0",
      "core-js": "^2.4.1",
      "jquery": "^3.1.1",
      "material-design-icons": "^3.0.0",
      "rxjs": "5.0.1",
      "systemjs": "0.19.40",
      "zone.js": "^0.7.4"
    },
    "devDependencies": {
      "@types/jasmine": "2.5.36",
      "@types/node": "^6.0.46",
      "canonical-path": "0.0.2",
      "concurrently": "^3.2.0",
      "gulp": "^3.9.1",
      "gulp-browserify": "^0.5.0",
      "gulp-clean": "^0.3.2",
      "gulp-debug": "^3.1.0",
      "gulp-ignore": "^2.0.2",
      "gulp-jshint": "^2.0.0",
      "gulp-livereload": "^3.8.1",
      "gulp-npm-files": "^0.1.3",
      "gulp-refresh": "^1.1.0",
      "gulp-sass": "^2.2.0",
      "gulp-sass-lint": "^1.3.2",
      "gulp-sequence": "^0.4.6",
      "gulp-typescript": "^3.1.5",
      "gulp-util": "^3.0.7",
      "jasmine-core": "~2.4.1",
      "jshint": "^2.9.2",
      "jshint-stylish": "^2.1.0",
      "karma": "^1.3.0",
      "karma-chrome-launcher": "^2.0.0",
      "karma-cli": "^1.0.1",
      "karma-jasmine": "^1.0.2",
      "karma-jasmine-html-reporter": "^0.2.2",
      "lite-server": "^2.2.2",
      "lodash": "^4.16.4",
      "protractor": "~4.0.14",
      "rimraf": "^2.5.4",
      "tslint": "^3.15.1",
      "typescript": "~2.0.10"
    },
    "repository": {}
  }
  </code></pre>