fix(module-loader-commonjs): avoid using fs to require commonjs module

docs/guides/feature-app-in-feature-app.md

@@ -39,10 +39,13 @@ added:
 ```
 
 And the integrator must provide `@feature-hub/react` and `react` as shared
-dependencies:
+dependencies.
+
+On the client:
 
 ```js
-import {defineExternals} from '@feature-hub/module-loader-amd';
+import {createFeatureHub} from '@feature-hub/core';
+import {defineExternals, loadAmdModule} from '@feature-hub/module-loader-amd';
 import * as FeatureHubReact from '@feature-hub/react';
 import * as React from 'react';
 ```
@@ -52,6 +55,28 @@ defineExternals({
   react: React,
   '@feature-hub/react': FeatureHubReact
 });
+
+const {featureAppManager} = createFeatureHub('acme:integrator', {
+  moduleLoader: loadAmdModule
+});
+```
+
+On the server:
+
+```js
+import {createFeatureHub} from '@feature-hub/core';
+import {createCommonJsModuleLoader} from '@feature-hub/module-loader-commonjs';
+import * as FeatureHubReact from '@feature-hub/react';
+import * as React from 'react';
+```
+
+```js
+const {featureAppManager} = createFeatureHub('acme:integrator', {
+  moduleLoader: createCommonJsModuleLoader({
+    react: React,
+    '@feature-hub/react': FeatureHubReact
+  })
+});
 ```
 
 [react-feature-app-container]:

docs/guides/sharing-npm-dependencies.md

@@ -15,11 +15,10 @@ using the `defineExternals` function:
 import {createFeatureHub} from '@feature-hub/core';
 import {defineExternals, loadAmdModule} from '@feature-hub/module-loader-amd';
 import * as React from 'react';
-import Loadable from 'react-loadable';
 ```
 
 ```js
-defineExternals({react: React, 'react-loadable': Loadable});
+defineExternals({react: React});
 
 const {featureAppManager} = createFeatureHub('acme:integrator', {
   moduleLoader: loadAmdModule
@@ -38,15 +37,35 @@ defining `react` as external in a webpack config would look like this:
 ```
 
 On the server, when Feature Apps are [bundled as CommonJS modules][serversrc],
-the integrator needs to make sure that the externals are provided as node
-modules that can be loaded with `require()`.
+the integrator either
+
+1. needs to make sure that the externals are provided as node modules that can
+   be loaded with `require()`, or
+
+1. if the integrator code is bundled and no node modules are available during
+   runtime, the integrator can provide shared npm dependencies to Feature Apps
+   using the `createCommonJsModuleLoader` function of the
+   [`@feature-hub/module-loader-commonjs`][module-loader-commonjs-api] package:
+
+   ```js
+   import {createFeatureHub} from '@feature-hub/core';
+   import {createCommonJsModuleLoader} from '@feature-hub/module-loader-commonjs';
+   import * as React from 'react';
+   ```
+
+   ```js
+   const {featureAppManager} = createFeatureHub('acme:integrator', {
+     moduleLoader: createCommonJsModuleLoader({react: React})
+   });
+   ```
 
 To validate the external dependencies that are [required by Feature
 Apps][feature-app-dependencies] against the shared npm dependencies that are
 provided by the integrator, [the `ExternalsValidator` can be
 used][validating-externals].
 
 [module-loader-amd-api]: /@feature-hub/modules/module_loader_amd.html
+[module-loader-commonjs-api]: /@feature-hub/modules/module_loader_commonjs.html
 [amd-module-loader-demo]:
   https://github.com/sinnerschrader/feature-hub/tree/master/packages/demos/src/module-loader-amd
 [serversrc]: /docs/guides/integrating-the-feature-hub#serversrc

packages/module-loader-commonjs/package.json

@@ -22,12 +22,10 @@
   "typings": "lib/cjs/index.d.ts",
   "dependencies": {
     "@feature-hub/core": "^2.2.0",
-    "fs-extra": "^8.0.0",
-    "node-fetch": "^2.3.0"
+    "node-fetch": "^2.6.0"
   },
   "devDependencies": {
-    "@types/fs-extra": "^8.0.0",
-    "@types/node-fetch": "^2.1.4"
+    "@types/node-fetch": "^2.3.7"
   },
   "publishConfig": {
     "access": "public"

packages/module-loader-commonjs/src/__tests__/index.test.ts

@@ -2,18 +2,18 @@
  * @jest-environment node
  */
 
+import {createCommonJsModuleLoader, loadCommonJsModule} from '..';
+
 let mockResponse: string;
 
 // tslint:disable promise-function-async
 jest.mock('node-fetch', () => () =>
   Promise.resolve({
-    buffer: () => Promise.resolve(Buffer.from(mockResponse))
+    text: () => Promise.resolve(Buffer.from(mockResponse))
   })
 );
 // tslint:enable promise-function-async
 
-import {loadCommonJsModule} from '..';
-
 describe('loadCommonJsModule (on Node.js)', () => {
   it('when a module is fetched successfully', async () => {
     const url = 'http://example.com/test.js';
@@ -31,3 +31,25 @@ describe('loadCommonJsModule (on Node.js)', () => {
     expect(loadedModule).toEqual(expectedModule);
   });
 });
+
+describe('createCommonJsModuleLoader', () => {
+  it('creates a CommonJS module loader with custom-defined externals', async () => {
+    const url = 'http://example.com/test.js';
+
+    mockResponse = `
+			var foo = require('foo');
+			module.exports = {
+				default: {test: foo()}
+			};
+		`;
+
+    const loadCommonJsModuleWithExternals = createCommonJsModuleLoader({
+      foo: () => 42
+    });
+
+    const loadedModule = await loadCommonJsModuleWithExternals(url);
+    const expectedModule = {default: {test: 42}};
+
+    expect(loadedModule).toEqual(expectedModule);
+  });
+});

packages/module-loader-commonjs/src/index.ts

@@ -1,42 +1,32 @@
 import {ModuleLoader} from '@feature-hub/core';
-import crypto from 'crypto';
-import fs from 'fs-extra';
 import fetch from 'node-fetch';
-import path from 'path';
 
-// This must be a local directory to make node module resolution possible.
-const tmpDirname = path.join(__dirname, '.tmp');
-
-function createHash(data: string): string {
-  return crypto
-    .createHash('md5')
-    .update(data)
-    .digest('hex');
-}
-
-async function writeFile(url: string, data: Buffer): Promise<string> {
-  /* istanbul ignore next */
-  if (!(await fs.pathExists(tmpDirname))) {
-    await fs.mkdirp(tmpDirname);
-  }
-
-  const filename = path.join(tmpDirname, `${createHash(url)}.js`);
-
-  await fs.writeFile(filename, data);
-
-  return filename;
+export interface Externals {
+  readonly [externalName: string]: unknown;
 }
 
-async function requireAsync(url: string): Promise<unknown> {
-  const response = await fetch(url);
-  const data = await response.buffer();
-  const filename = await writeFile(url, data);
-
-  // Make sure no stale version of the module is loaded from the require cache!
-  // tslint:disable-next-line:no-dynamic-delete
-  delete require.cache[require.resolve(filename)];
-
-  return require(filename);
+export function createCommonJsModuleLoader(
+  externals: Externals = {}
+): ModuleLoader {
+  return async (url: string): Promise<unknown> => {
+    const response = await fetch(url);
+    const source = await response.text();
+    const mod = {exports: {}};
+
+    // tslint:disable-next-line:function-constructor
+    Function(
+      'module',
+      'exports',
+      'require',
+      `${source}
+      //# sourceURL=${url}`
+    )(mod, mod.exports, (dep: string) =>
+      // tslint:disable-next-line:no-eval https://stackoverflow.com/a/41063795/10385541
+      externals.hasOwnProperty(dep) ? externals[dep] : eval('require')(dep)
+    );
+
+    return mod.exports;
+  };
 }
 
-export const loadCommonJsModule: ModuleLoader = async url => requireAsync(url);
+export const loadCommonJsModule: ModuleLoader = createCommonJsModuleLoader();

yarn.lock

@@ -2194,13 +2194,6 @@
     "@types/express-serve-static-core" "*"
     "@types/serve-static" "*"
 
-"@types/fs-extra@^8.0.0":
-  version "8.0.0"
-  resolved "https://registry.yarnpkg.com/@types/fs-extra/-/fs-extra-8.0.0.tgz#d3e2c313ca29f95059f198dd60d1f774642d4b25"
-  integrity sha512-bCtL5v9zdbQW86yexOlXWTEGvLNqWxMFyi7gQA7Gcthbezr2cPSOb8SkESVKA937QD5cIwOFLDFt0MQoXOEr9Q==
-  dependencies:
-    "@types/node" "*"
-
 "@types/get-port@^4.0.0":
   version "4.2.0"
   resolved "https://registry.yarnpkg.com/@types/get-port/-/get-port-4.2.0.tgz#4fc44616c737d37d3ee7926d86fa975d0afba5e4"
@@ -2288,10 +2281,10 @@
   resolved "https://registry.yarnpkg.com/@types/minimatch/-/minimatch-3.0.3.tgz#3dca0e3f33b200fc7d1139c0cd96c1268cadfd9d"
   integrity sha512-tHq6qdbT9U1IRSGf14CL0pUlULksvY9OZ+5eEgl1N7t+OA3tGvNpxJCzuKQlsNgCVwbAs670L1vcVQi8j9HjnA==
 
-"@types/node-fetch@^2.1.4":
-  version "2.3.7"
-  resolved "https://registry.yarnpkg.com/@types/node-fetch/-/node-fetch-2.3.7.tgz#b7212e895100f8642dbdab698472bab5f3c1d2f1"
-  integrity sha512-+bKtuxhj/TYSSP1r4CZhfmyA0vm/aDRQNo7vbAgf6/cZajn0SAniGGST07yvI4Q+q169WTa2/x9gEHfJrkcALw==
+"@types/node-fetch@^2.3.7":
+  version "2.5.0"
+  resolved "https://registry.yarnpkg.com/@types/node-fetch/-/node-fetch-2.5.0.tgz#1c55616a4591bdd15a389fbd0da4a55b9502add5"
+  integrity sha512-TLFRywthBgL68auWj+ziWu+vnmmcHCDFC/sqCOQf1xTz4hRq8cu79z8CtHU9lncExGBsB8fXA4TiLDLt6xvMzw==
   dependencies:
     "@types/node" "*"
 
@@ -6243,7 +6236,7 @@ fs-extra@^7.0.0:
     jsonfile "^4.0.0"
     universalify "^0.1.0"
 
-fs-extra@^8.0.0, fs-extra@^8.1.0:
+fs-extra@^8.1.0:
   version "8.1.0"
   resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-8.1.0.tgz#49d43c45a88cd9677668cb7be1b46efdb8d2e1c0"
   integrity sha512-yhlQgA6mnOJUKOsRUFsgJdQCvkKhcz8tlZG5HBQfReYZy46OwLcY+Zia0mtdHsOo9y/hP+CxMN0TU9QxoOtG4g==
@@ -9414,7 +9407,7 @@ node-fetch@^1.0.1:
     encoding "^0.1.11"
     is-stream "^1.0.1"
 
-node-fetch@^2.3.0, node-fetch@^2.5.0:
+node-fetch@^2.3.0, node-fetch@^2.5.0, node-fetch@^2.6.0:
   version "2.6.0"
   resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-2.6.0.tgz#e633456386d4aa55863f676a7ab0daa8fdecb0fd"
   integrity sha512-8dG4H5ujfvFiqDmVu9fQ5bOHUC15JMjMY/Zumv26oOvvVJjM67KF8koCWIabKQ1GJIa9r2mMZscBq/TbdOcmNA==