fix: asynchronously create packager instance (#352)

src/pack-externals.ts

@@ -1,5 +1,6 @@
-import fse from 'fs-extra';
 import path from 'path';
+
+import fse from 'fs-extra';
 import {
   compose,
   forEach,
@@ -24,11 +25,11 @@ import {
   without,
 } from 'ramda';
 
-import * as Packagers from './packagers';
-import { JSONObject } from './types';
+import { getPackager } from './packagers';
 import { findProjectRoot, findUp } from './utils';
 
-import EsbuildServerlessPlugin from './index';
+import type EsbuildServerlessPlugin from './index';
+import type { JSONObject } from './types';
 
 function rebaseFileReferences(pathToPackageRoot: string, moduleVersion: string) {
   if (/^(?:file:[^/]{2}|\.\/|\.\.\/)/.test(moduleVersion)) {
@@ -242,7 +243,7 @@ export async function packExternalModules(this: EsbuildServerlessPlugin) {
     path.relative(process.cwd(), path.join(findUp('package.json'), './package.json'));
 
   // Determine and create packager
-  const packager = await Packagers.get(this.buildOptions.packager);
+  const packager = await getPackager.call(this, this.buildOptions.packager);
 
   // Fetch needed original package.json sections
   const sectionNames = packager.copyPackageSectionNames;

src/pack.ts

@@ -1,6 +1,7 @@
+import path from 'path';
+
 import fs from 'fs-extra';
 import globby from 'globby';
-import path from 'path';
 import {
   intersection,
   isEmpty,
@@ -14,13 +15,15 @@ import {
   without,
 } from 'ramda';
 import semver from 'semver';
-import EsbuildServerlessPlugin from '.';
+
 import { ONLY_PREFIX, SERVERLESS_FOLDER } from './constants';
 import { doSharePath, flatDep, getDepsFromBundle, isESM } from './helper';
-import * as Packagers from './packagers';
-import { IFiles } from './types';
+import { getPackager } from './packagers';
 import { humanSize, zip, trimExtension } from './utils';
 
+import type EsbuildServerlessPlugin from './index';
+import type { IFiles } from './types';
+
 function setFunctionArtifactPath(this: EsbuildServerlessPlugin, func, artifactPath) {
   const version = this.serverless.getVersion();
   // Serverless changed the artifact path location in version 1.18
@@ -137,7 +140,7 @@ export async function pack(this: EsbuildServerlessPlugin) {
   }
 
   // 2) If individually is set, we'll optimize files and zip per-function
-  const packager = await Packagers.get(this.buildOptions.packager);
+  const packager = await getPackager.call(this, this.buildOptions.packager);
 
   // get a list of every function bundle
   const buildResults = this.buildResults;

src/packagers/index.ts

@@ -1,44 +1,58 @@
 /**
  * Factory for supported packagers.
  *
- * All packagers must implement the following interface:
+ * All packagers must extend the Packager class.
  *
- * interface Packager {
- *
- * static get lockfileName(): string;
- * static get copyPackageSectionNames(): Array<string>;
- * static get mustCopyModules(): boolean;
- * static getProdDependencies(cwd: string, depth: number = 1): BbPromise<Object>;
- * static rebaseLockfile(pathToPackageRoot: string, lockfile: Object): void;
- * static install(cwd: string): BbPromise<void>;
- * static prune(cwd: string): BbPromise<void>;
- * static runScripts(cwd: string, scriptNames): BbPromise<void>;
- *
- * }
+ * @see Packager
  */
+import { memoizeWith } from 'ramda';
+
+import { isPackagerId } from '../type-predicate';
+
+import type EsbuildServerlessPlugin from '../index';
+import type { PackagerId } from '../types';
+import type { Packager } from './packager';
+
+const packagerFactories: Record<PackagerId, () => Promise<Packager>> = {
+  async npm() {
+    const { NPM } = await import('./npm');
+
+    return new NPM();
+  },
+  async pnpm() {
+    const { Pnpm } = await import('./pnpm');
 
-import { Packager } from './packager';
-import { NPM } from './npm';
-import { Pnpm } from './pnpm';
-import { Yarn } from './yarn';
+    return new Pnpm();
+  },
+  async yarn() {
+    const { Yarn } = await import('./yarn');
 
-const registeredPackagers = {
-  npm: new NPM(),
-  pnpm: new Pnpm(),
-  yarn: new Yarn(),
+    return new Yarn();
+  },
 };
 
 /**
- * Factory method.
- * @this ServerlessWebpack - Active plugin instance
- * @param {string} packagerId - Well known packager id.
- * @returns {Promise<Packager>} - Promised packager to allow packagers be created asynchronously.
+ * Asynchronously create a Packager instance and memoize it.
+ *
+ * @this EsbuildServerlessPlugin - Active plugin instance
+ * @param {string} packagerId - Well known packager id
+ * @returns {Promise<Packager>} - The selected Packager
  */
-export function get(packagerId: string): Promise<Packager> {
-  if (!(packagerId in registeredPackagers)) {
-    const message = `Could not find packager '${packagerId}'`;
-    this.log.error(`ERROR: ${message}`);
-    throw new this.serverless.classes.Error(message);
+export const getPackager = memoizeWith(
+  (packagerId) => packagerId,
+  async function (this: EsbuildServerlessPlugin, packagerId: PackagerId): Promise<Packager> {
+    this.log.debug(`Trying to create packager: ${packagerId}`);
+
+    if (!isPackagerId(packagerId)) {
+      // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+      // @ts-ignore Serverless typings (as of v3.0.2) are incorrect
+      throw new this.serverless.classes.Error(`Could not find packager '${packagerId}'`);
+    }
+
+    const packager = await packagerFactories[packagerId]();
+
+    this.log.debug(`Packager created: ${packagerId}`);
+
+    return packager;
   }
-  return registeredPackagers[packagerId];
-}
+);

src/tests/packagers/index.test.ts

@@ -0,0 +1,17 @@
+import { getPackager } from '../../packagers';
+
+import type EsbuildServerlessPlugin from '../../index';
+
+describe('getPackager()', () => {
+  const mockPlugin = {
+    log: {
+      debug: jest.fn(),
+    },
+  } as unknown as EsbuildServerlessPlugin;
+
+  it('Returns a Packager instance', async () => {
+    const npm = await getPackager.call(mockPlugin, 'npm');
+
+    expect(npm).toEqual(expect.any(Object));
+  });
+});

src/tests/type-predicate.test.ts

@@ -0,0 +1,15 @@
+import { isPackagerId } from '../type-predicate';
+
+describe('isPackagerId()', () => {
+  it('Returns true for valid input', () => {
+    ['npm', 'pnpm', 'yarn'].forEach((id) => {
+      expect(isPackagerId(id)).toBeTruthy();
+    });
+  });
+
+  it('Returns false for invalid input', () => {
+    ['not-a-real-packager-id', false, 123, [], {}].forEach((id) => {
+      expect(isPackagerId(id)).toBeFalsy();
+    });
+  });
+});

src/type-predicate.ts

@@ -0,0 +1,5 @@
+import type { PackagerId } from './types';
+
+export function isPackagerId(input: unknown): input is PackagerId {
+  return input === 'npm' || input === 'pnpm' || input === 'yarn';
+}

src/types.ts

@@ -1,5 +1,5 @@
-import { BuildOptions, BuildResult, Plugin } from 'esbuild';
-import Serverless from 'serverless';
+import type { BuildOptions, BuildResult, Plugin } from 'esbuild';
+import type Serverless from 'serverless';
 
 export type ConfigFn = (sls: Serverless) => Configuration;
 
@@ -74,3 +74,5 @@ export interface IFile {
   readonly rootPath: string;
 }
 export type IFiles = readonly IFile[];
+
+export type PackagerId = 'npm' | 'pnpm' | 'yarn';