Merge pull request #1495 from aldenquimby/fix-1493-alternative

Allow generating ESM output from npm (non-breaking)

README.md

@@ -406,28 +406,46 @@ you should use any version `<5.5 >=5.7.1` as the versions in-between have some n
 
 The NPM packager supports the following `packagerOptions`:
 
-| Option             | Type   | Default               | Description                                         |
-| ------------------ | ------ | --------------------- | --------------------------------------------------- |
-| ignoreScripts      | bool   | false                 | Do not execute package.json hook scripts on install |
-| noInstall          | bool   | false                 | Do not run `npm install` (assume install completed) |
-| lockFile           | string | ./package-lock.json   | Relative path to lock file to use                   |
+| Option                  | Type     | Default             | Description                                                         |
+|-------------------------|----------|---------------------|---------------------------------------------------------------------|
+| ignoreScripts           | bool     | false               | Do not execute package.json hook scripts on install                 |
+| noInstall               | bool     | false               | Do not run `npm install` (assume install completed)                 |
+| lockFile                | string   | ./package-lock.json | Relative path to lock file to use                                   |
+| copyPackageSectionNames | string[] | []                  | Entries in your `package.json` to copy to the output `package.json` (ie: ESM output) |
 
 When using NPM version `>= 7.0.0`, we will use the `package-lock.json` file instead of modules installed in `node_modules`. This improves the
 supports of NPM `>= 8.0.0` which installs `peer-dependencies` automatically. The plugin will be able to detect the correct version.
 
+###### ESM output
+
+If you need to generate ESM output, and you cannot safely produce a `.mjs` file
+(e.g. [because that breaks serverless-offline](https://github.com/serverless/serverless/issues/11308)),
+you can use `copyPackageSectionNames` to ensure the output `package.json` defaults to ESM.
+
+```yaml
+custom:
+  webpack:
+    packagerOptions:
+      copyPackageSectionNames:
+        - type
+        - exports
+        - main
+```
+
 ##### Yarn
 
 Using yarn will switch the whole packaging pipeline to use yarn, so does it use a `yarn.lock` file.
 
 The yarn packager supports the following `packagerOptions`:
 
-| Option             | Type | Default | Description                                         |
-| ------------------ | ---- | ------- | --------------------------------------------------- |
-| ignoreScripts      | bool | false   | Do not execute package.json hook scripts on install |
-| noInstall          | bool | false   | Do not run `yarn install` (assume install completed)|
-| noNonInteractive   | bool | false   | Disable interactive mode when using Yarn 2 or above |
-| noFrozenLockfile   | bool | false   | Do not require an up-to-date yarn.lock              |
-| networkConcurrency | int  |         | Specify number of concurrent network requests       |
+| Option                  | Type     | Default         | Description                                                         |
+|-------------------------|----------|-----------------|---------------------------------------------------------------------|
+| ignoreScripts           | bool     | false           | Do not execute package.json hook scripts on install                 |
+| noInstall               | bool     | false           | Do not run `yarn install` (assume install completed)                |
+| noNonInteractive        | bool     | false           | Disable interactive mode when using Yarn 2 or above                 |
+| noFrozenLockfile        | bool     | false           | Do not require an up-to-date yarn.lock                              |
+| networkConcurrency      | int      |                 | Specify number of concurrent network requests                       |
+| copyPackageSectionNames | string[] | ['resolutions'] | Entries in your `package.json` to copy to the output `package.json` |
 
 ##### Common packager options
 

lib/packExternalModules.js

@@ -266,7 +266,7 @@ module.exports = {
     // Determine and create packager
     return BbPromise.try(() => Packagers.get.call(this, this.configuration.packager)).then(packager => {
       // Fetch needed original package.json sections
-      const sectionNames = packager.copyPackageSectionNames;
+      const sectionNames = packager.copyPackageSectionNames(this.configuration.packagerOptions);
       const packageJson = this.serverless.utils.readFileSync(packageJsonPath);
       const packageSections = _.pick(packageJson, sectionNames);
       if (!_.isEmpty(packageSections)) {

lib/packagers/index.js

@@ -7,8 +7,8 @@
  * interface Packager {
  *
  * static get lockfileName(): string;
- * static get copyPackageSectionNames(): Array<string>;
  * static get mustCopyModules(): boolean;
+ * static copyPackageSectionNames(packagerOptions: Object): Array<string>;
  * static getPackagerVersion(cwd: string): BbPromise<Object>
  * static getProdDependencies(cwd: string, depth: number = 1): BbPromise<Object>;
  * static rebaseLockfile(pathToPackageRoot: string, lockfile: Object): void;

lib/packagers/npm.js

@@ -16,15 +16,16 @@ class NPM {
     return 'package-lock.json';
   }
 
-  static get copyPackageSectionNames() {
-    return [];
-  }
-
   // eslint-disable-next-line lodash/prefer-constant
   static get mustCopyModules() {
     return true;
   }
 
+  static copyPackageSectionNames(packagerOptions) {
+    const options = packagerOptions || {};
+    return options.copyPackageSectionNames || [];
+  }
+
   static getPackagerVersion(cwd) {
     const command = /^win/.test(process.platform) ? 'npm.cmd' : 'npm';
     const args = ['-v'];

lib/packagers/yarn.js

@@ -21,15 +21,16 @@ class Yarn {
     return 'yarn.lock';
   }
 
-  static get copyPackageSectionNames() {
-    return ['resolutions'];
-  }
-
   // eslint-disable-next-line lodash/prefer-constant
   static get mustCopyModules() {
     return false;
   }
 
+  static copyPackageSectionNames(packagerOptions) {
+    const options = packagerOptions || {};
+    return options.copyPackageSectionNames || ['resolutions'];
+  }
+
   static isBerryVersion(version) {
     const versionNumber = version.charAt(0);
     const mainVersion = parseInt(versionNumber);

tests/packExternalModules.test.js

@@ -18,7 +18,7 @@ jest.mock('fs-extra');
 jest.mock('../lib/packagers/index', () => {
   const packagerMock = {
     lockfileName: 'mocked-lock.json',
-    copyPackageSectionNames: ['section1', 'section2'],
+    copyPackageSectionNames: jest.requireActual('../lib/packagers/npm').copyPackageSectionNames,
     mustCopyModules: true,
     rebaseLockfile: jest.fn(),
     getPackagerVersion: jest.fn(),
@@ -196,6 +196,15 @@ describe('packExternalModules', () => {
         section1: originalPackageJSON.section1
       };
 
+      module.configuration = new Configuration({
+        webpack: {
+          includeModules: true,
+          packager: 'npm',
+          packagerOptions: {
+            copyPackageSectionNames: ['section1', 'section2']
+          }
+        }
+      });
       module.webpackOutputPath = '/my/Service/Path/outputPath';
       readFileSyncStub.mockReturnValueOnce(originalPackageJSON);
       readFileSyncStub.mockImplementation(() => {
@@ -229,6 +238,79 @@ describe('packExternalModules', () => {
         );
     });
 
+    it('should include ESM type from package.json according to packagerOptions', () => {
+      const originalPackageJSON = {
+        name: 'test-service',
+        version: '1.0.0',
+        description: 'Packaged externals for test-service',
+        private: true,
+        type: 'module',
+        dependencies: {
+          '@scoped/vendor': '1.0.0',
+          bluebird: '^3.4.0',
+          uuid: '^5.4.1'
+        }
+      };
+      const expectedCompositePackageJSON = {
+        name: 'test-service',
+        version: '1.0.0',
+        description: 'Packaged externals for test-service',
+        private: true,
+        scripts: {},
+        type: 'module',
+        dependencies: {
+          '@scoped/vendor': '1.0.0',
+          bluebird: '^3.4.0',
+          uuid: '^5.4.1'
+        }
+      };
+      const expectedPackageJSON = {
+        name: 'test-service',
+        version: '1.0.0',
+        description: 'Packaged externals for test-service',
+        private: true,
+        scripts: {},
+        dependencies: {
+          '@scoped/vendor': '1.0.0',
+          bluebird: '^3.4.0',
+          uuid: '^5.4.1'
+        },
+        type: 'module'
+      };
+      module.configuration = new Configuration({
+        webpack: {
+          includeModules: true,
+          packager: 'npm',
+          packagerOptions: {
+            copyPackageSectionNames: ['type']
+          }
+        }
+      });
+
+      module.webpackOutputPath = '/my/Service/Path/outputPath';
+      fsExtraMock.pathExists.mockImplementation((p, cb) => cb(null, true));
+      fsExtraMock.copy.mockImplementation((from, to, cb) => cb());
+      readFileSyncStub.mockReturnValueOnce(originalPackageJSON);
+      readFileSyncStub.mockImplementation(() => {
+        throw new Error('Unexpected call to readFileSync');
+      });
+      packagerFactoryMock.get('npm').rebaseLockfile.mockImplementation((pathToPackageRoot, lockfile) => lockfile);
+      packagerFactoryMock.get('npm').getProdDependencies.mockReturnValue(BbPromise.resolve({}));
+      packagerFactoryMock.get('npm').install.mockReturnValue(BbPromise.resolve());
+      packagerFactoryMock.get('npm').prune.mockReturnValue(BbPromise.resolve());
+      packagerFactoryMock.get('npm').runScripts.mockReturnValue(BbPromise.resolve());
+      module.compileStats = stats;
+      return expect(module.packExternalModules())
+        .resolves.toBeUndefined()
+        .then(() =>
+          BbPromise.all([
+            expect(writeFileSyncStub).toHaveBeenCalledTimes(2),
+            expect(writeFileSyncStub.mock.calls[0][1]).toEqual(JSON.stringify(expectedCompositePackageJSON, null, 2)),
+            expect(writeFileSyncStub.mock.calls[1][1]).toEqual(JSON.stringify(expectedPackageJSON, null, 2))
+          ])
+        );
+    });
+
     it('should install external modules', () => {
       const expectedCompositePackageJSON = {
         name: 'test-service',

tests/packagers/npm.test.js

@@ -30,8 +30,12 @@ describe('npm', () => {
     expect(npmModule.lockfileName).toEqual('package-lock.json');
   });
 
-  it('should return no packager sections', () => {
-    expect(npmModule.copyPackageSectionNames).toEqual([]);
+  it('should return no packager sections by default', () => {
+    expect(npmModule.copyPackageSectionNames()).toEqual([]);
+  });
+
+  it('should return packager sections from config', () => {
+    expect(npmModule.copyPackageSectionNames({ copyPackageSectionNames: ['type'] })).toEqual(['type']);
   });
 
   it('requires to copy modules', () => {

tests/packagers/yarn.test.js

@@ -21,7 +21,11 @@ describe('yarn', () => {
   });
 
   it('should return packager sections', () => {
-    expect(yarnModule.copyPackageSectionNames).toEqual(['resolutions']);
+    expect(yarnModule.copyPackageSectionNames()).toEqual(['resolutions']);
+  });
+
+  it('should return packager sections from config', () => {
+    expect(yarnModule.copyPackageSectionNames({ copyPackageSectionNames: ['type'] })).toEqual(['type']);
   });
 
   it('does not require to copy modules', () => {