WIP: test: add tree-shaking test (angular#8979)

* test: add tree-shaking test

currently this doesn't throw or break the build, first we need to resolve all
of the existing issues.

to run execute: ./tools/tree-shaking-test/test.sh

then inspect dist/tree-shaking/test/**/*.bundle.js

* fix(http): remove peerDep on @angular/common

it is not needed there because it will get transitively installed by @angular/platform-browser

we only need to declare this dependency in tsconfig.json because tsconfig.json's
do not support transitive dependencies in this way.

Author: IgorMinar

modules/@angular/http/package.json

@@ -10,7 +10,6 @@
   "peerDependencies": {
     "rxjs": "5.0.0-beta.6",
     "@angular/core": "0.0.0-PLACEHOLDER",
-    "@angular/common": "0.0.0-PLACEHOLDER",
     "@angular/platform-browser": "0.0.0-PLACEHOLDER"
   },
   "repository": {

tools/tree-shaking-test/README.md

@@ -0,0 +1,17 @@
+Rollup tree-shaking test
+------------------------
+
+The purpose of this test is to verify how much stuff can be tree-shaken from our packages.
+
+The test generates an empty js file that imports everything from a particular package but doesn't
+use any of the imported references.
+
+In the ideal scenario Rollup should detect that none of the references are being used and should
+create an empty bundle file.
+
+In reality there is a lot of stuff preserved in the bundle because Rollup is currently not able to
+make a safe decision to remove many of the unused symbols.
+
+To run execute: `./tools/tree-shaking-test/test.sh`
+
+then inspect `dist/tree-shaking/test/**/*.bundle.js`

tools/tree-shaking-test/rollup.config.js

@@ -0,0 +1,20 @@
+class RollupNG2 {
+  resolveId(id, from){
+    if(id.startsWith('@angular/')){
+      return `${__dirname}/../../packages-dist/${id.split('/')[1]}/esm/index.js`;
+    }
+
+    // if(id.startsWith('rxjs/')){
+    //   return `${__dirname}/../../../node_modules/rxjs-es/${id.replace('rxjs/', '')}.js`;
+    // }
+  }
+}
+
+
+export default {
+  entry: 'test.js',
+  format: 'es6',
+  plugins: [
+    new RollupNG2(),
+  ]
+}

tools/tree-shaking-test/test.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+set -ex -o pipefail
+
+cd `dirname $0`
+cd ../..
+
+export NODE_PATH=${NODE_PATH}:$(pwd)/dist-packages/
+
+DEST_DIR=./dist/trees-shaking-test
+
+rm -rf ${DEST_DIR}
+
+for PACKAGE in \
+  core \
+  compiler \
+  common \
+  platform-browser \
+  platform-server \
+  http \
+  router \
+  upgrade
+do
+  echo "=======    Tree-shaking TEST: ${SRCDIR} ====="
+  TEST_DIR=${DEST_DIR}/${PACKAGE}
+  TEST_ENTRY_POINT=${TEST_DIR}/test.js
+  mkdir -p ${TEST_DIR}
+  cp ./tools/tree-shaking-test/rollup.config.js ${TEST_DIR}/
+  echo "import * as x from '@angular/${PACKAGE}'" > ${TEST_ENTRY_POINT}
+  (
+    cd ${TEST_DIR}
+    $(npm bin)/rollup --config rollup.config.js --output ${PACKAGE}.bundle.js
+  )
+
+done