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', () => {