Add support for esbuild code splitting

Author: doteric

.gitignore

@@ -1,5 +1,5 @@
 node_modules/
-dist/
+dist*/
 coverage/
 
 .DS_store

example/second.ts

@@ -2,6 +2,8 @@ import rimraf from 'rimraf';
 
 export const addTest = (a: number, b: number) => a + b;
 
-export const test = () => {
+const test = () => {
   console.log('rimraf', rimraf);
 };
+
+export default test;

example/test.ts

@@ -1,5 +1,12 @@
-import { addTest } from './second';
+const test = {
+  second: () => import('./second'),
+  third: () => import('./third'),
+};
+
+type testKeysType = keyof typeof test;
 
-export const handler = () => {
-  console.log(addTest(1, 3));
+export const handler = async (payload: unknown = 'second') => {
+  if (typeof payload === 'string' && payload in test) {
+    test[payload as testKeysType]();
+  }
 };

example/third.ts

@@ -0,0 +1,3 @@
+const justForTest = () => console.log('Example');
+
+export default justForTest;

package-lock.json

@@ -49,7 +49,7 @@
   "dependencies": {
     "archiver": "^5.3.1",
     "commander": "^9.3.0",
-    "esbuild": "^0.14.43",
+    "esbuild": "^0.15.13",
     "zod": "^3.17.3"
   }
 }

package.json

@@ -17,12 +17,13 @@ const buildFunction = async (
   const esbuildConfig: BuildOptions =
     packageObject.funpack.settings.esbuildConfigOverride;
   const outputDir = packageObject.funpack.settings.outputDir;
-  const outputFilePath = join(outputDir, name, OUTPUT_FILE_NAME);
+  const functionOutputDir = join(outputDir, name);
 
   // Use esbuild to compile the function
   const buildResult = await useEsbuild(
     entrypoint,
-    outputFilePath,
+    functionOutputDir,
+    OUTPUT_FILE_NAME.replace('.js', ''),
     esbuildConfig
   );
 
@@ -32,6 +33,7 @@ const buildFunction = async (
     error('Missing metafile in esbuild result!');
     return false;
   }
+  const outputFilePath = join(outputDir, name, OUTPUT_FILE_NAME);
   generatePackageJson(
     metafile,
     packageObject,

src/bulidFunction.ts

@@ -1,21 +1,20 @@
 import { join } from 'path';
 
-import funpack from './index';
+import funpack from '../index';
 
 process.env.GIT_REPO_URL = 'https://example.com/test/repo.git';
 
-jest.mock('./utils/getPackageJsonObject', () =>
+jest.mock('../utils/getPackageJsonObject', () =>
   jest.fn().mockReturnValue({
     name: 'my-lambdas',
     version: '0.0.0-dev',
-    type: 'module',
     funpack: {
       settings: {
         outputDir: 'example/dist',
         packageFieldsToCopy: ['version', 'type'],
         cleanupOutputDir: true,
         zip: true,
-        removeDirAfterZip: true,
+        //removeDirAfterZip: true,
         customPackageFields: {
           repository: {
             type: 'git',
@@ -39,13 +38,13 @@ describe('funpack', () => {
     expect(console.log).toBeCalledWith(
       join('example', 'dist', 'testfunc.zip'),
       '-',
-      20771,
+      21113,
       'total bytes'
     );
     expect(console.log).toBeCalledWith(
       join('example', 'dist', 'second.zip'),
       '-',
-      20768,
+      20815,
       'total bytes'
     );
   });

src/index.test.ts src/packTests/basic.test.tssrc/index.test.ts renamed to src/packTests/basic.test.ts

@@ -0,0 +1,52 @@
+import { join } from 'path';
+
+import funpack from '../index';
+
+process.env.GIT_REPO_URL = 'https://example.com/test/repo.git';
+
+// TODO: Change to using full examples instead of mocking like that
+jest.mock('../utils/getPackageJsonObject', () =>
+  jest.fn().mockReturnValue({
+    name: 'my-lambdas',
+    version: '0.0.0-dev',
+    type: 'module',
+    funpack: {
+      settings: {
+        outputDir: 'example/dist-splitting',
+        packageFieldsToCopy: ['version', 'type'],
+        cleanupOutputDir: true,
+        zip: true,
+        esbuildConfigOverride: {
+          format: 'esm',
+          target: 'node16',
+          splitting: true,
+          sourcemap: true,
+        },
+      },
+      functions: {
+        firstSplit: './example/test.ts',
+        secondSplit: './example/second.ts',
+      },
+    },
+  })
+);
+
+describe('funpack', () => {
+  console.log = jest.fn();
+  it('builds correctly', async () => {
+    await funpack();
+    // TODO: Improve test case to check for files?
+    expect(console.log).toHaveBeenCalledTimes(2);
+    const logMock = console.log as jest.Mock;
+
+    expect(logMock.mock.calls[0][0]).toBe(
+      join('example', 'dist-splitting', 'secondSplit.zip')
+    );
+    expect(logMock.mock.calls[0][2]).toBeCloseTo(67352, -2);
+
+    expect(logMock.mock.calls[1][0]).toBe(
+      join('example', 'dist-splitting', 'firstSplit.zip')
+    );
+    expect(logMock.mock.calls[1][2]).toBeCloseTo(69275, -2);
+  });
+});

src/packTests/splitting.test.ts

@@ -3,14 +3,17 @@ import type { BuildOptions } from 'esbuild';
 
 const useEsbuild = async (
   entrypoint: string,
-  outfile: string,
+  outputDir: string,
+  outputName: string,
   esbuildConfig: BuildOptions = {}
 ) => {
   const result = await build({
-    entryPoints: [entrypoint],
+    entryPoints: {
+      [outputName]: entrypoint,
+    },
+    outdir: outputDir,
     bundle: true,
     platform: 'node',
-    outfile,
     metafile: true,
     ...esbuildConfig,
   });