Add config/test app for new PR stats set-up (#8317)

* Add config/test app for new PR stats set-up

* Move config/test app to test folder

test/.stats-app/package.json

+{
+  "name": "stats-app",
+  "version": "1.0.0",
+  "main": "index.js",
+  "license": "MIT",
+  "dependencies": {
+    "next": "latest",
+    "react": "16.9.0",
+    "react-dom": "16.9.0"
+  }
+}

test/.stats-app/pages/index.js

+const Page = () => 'Hello world 👋'
+
+Page.getInitialProps = () => ({})
+
+export default Page

test/.stats-app/pages/link.js

+import Link from 'next/link'
+
+function aLink (props) {
+  return (
+    <div>
+      <h3>A Link page!</h3>
+      <Link href='/'>Go to /</Link>
+    </div>
+  )
+}
+
+aLink.getInitialProps = () => ({})
+
+export default aLink

test/.stats-app/pages/routerDirect.js

+/* eslint-disable-next-line */
+import Router from 'next/router'
+
+function routerDirect (props) {
+  return <div>I import the router directly</div>
+}
+
+routerDirect.getInitialProps = () => ({})
+
+export default routerDirect

test/.stats-app/pages/withRouter.js

+import { withRouter } from 'next/router'
+
+function useWithRouter (props) {
+  return <div>I use withRouter</div>
+}
+
+useWithRouter.getInitialProps = () => ({})
+
+export default withRouter(useWithRouter)

test/.stats-app/stats-config.js

+const clientGlobs = [
+  {
+    name: 'Client Bundles (main, webpack, commons)',
+    globs: [
+      '.next/static/runtime/+(main|webpack)-!(*.module.js)',
+      '.next/static/chunks/commons!(*.module.js)'
+    ]
+  },
+  {
+    name: 'Client Bundles (main, webpack, commons) Modern',
+    globs: [
+      '.next/static/runtime/+(main|webpack)-*.module.js',
+      '.next/static/chunks/commons.*.module.js'
+    ]
+  },
+  {
+    name: 'Client Pages',
+    globs: ['.next/static/*/pages/**/!(*.module.js)']
+  },
+  {
+    name: 'Client Pages Modern',
+    globs: ['.next/static/*/pages/**/*.module.js']
+  }
+]
+
+const renames = [
+  {
+    srcGlob: '.next/static/*/pages',
+    dest: '.next/static/BUILD_ID/pages'
+  },
+  {
+    srcGlob: '.next/static/runtime/main-!(*.module.js)',
+    dest: '.next/static/runtime/main-HASH.js'
+  },
+  {
+    srcGlob: '.next/static/runtime/webpack-!(*.module.js)',
+    dest: '.next/static/runtime/webpack-HASH.js'
+  },
+  {
+    srcGlob: '.next/static/chunks/commons!(*.module.js)',
+    dest: 'next/static/chunks/commons-HASH.js'
+  },
+  // modern
+  {
+    srcGlob: '.next/static/runtime/main-*.module.js',
+    dest: '.next/static/runtime/main-HASH.module.js'
+  },
+  {
+    srcGlob: '.next/static/runtime/webpack-*.module.js',
+    dest: '.next/static/runtime/webpack-HASH.module.js'
+  },
+  {
+    srcGlob: '.next/static/chunks/commons*.module.js',
+    dest: 'next/static/chunks/commons.HASH.module.js'
+  }
+]
+
+module.exports = {
+  commentHeading: 'Stats from current PR',
+  commentReleaseHeading: 'Stats from current release',
+  appBuildCommand: 'yarn next build',
+  appStartCommand: 'yarn next start',
+  mainRepo: 'zeit/next.js',
+  mainBranch: 'canary',
+  autoMergeMain: true,
+  configs: [
+    {
+      title: 'Default Server Mode',
+      diff: 'onOutputChange',
+      diffConfigFiles: [
+        {
+          path: 'next.config.js',
+          content: `
+            module.exports = {
+              webpack(config) {
+                config.optimization.minimize = false
+                config.optimization.minimizer = undefined
+                return config
+              },
+              experimental: {
+                modern: true
+              }
+            }
+          `
+        }
+      ],
+      // renames to apply to make file names deterministic
+      renames,
+      configFiles: [
+        {
+          path: 'next.config.js',
+          content: `
+            module.exports = {
+              experimental: {
+                modern: true
+              }
+            }
+          `
+        }
+      ],
+      filesToTrack: clientGlobs,
+      pagesToFetch: [
+        'http://localhost:3000/link',
+        'http://localhost:3000/index',
+        'http://localhost:3000/withRouter'
+      ]
+    },
+    {
+      title: 'Serverless Mode',
+      diff: false,
+      renames,
+      configFiles: [
+        {
+          path: 'next.config.js',
+          content: `
+            module.exports = {
+              target: 'serverless',
+              experimental: {
+                modern: true
+              }
+            }
+          `
+        }
+      ],
+      filesToTrack: [
+        ...clientGlobs,
+        {
+          name: 'Serverless bundles',
+          globs: ['.next/serverless/pages/**/*']
+        }
+      ]
+    }
+  ]
+}