feat: ESM emulation over Babel (#20)

Author: noomorph

__fixtures__/simple-project/.esbuild-jestrc.js

@@ -4,9 +4,6 @@ module.exports = {
     "sourcemap": true,
     "platform": "node",
     "outdir": "../simple-project-bundled",
-    "outExtension": {
-      ".js": ".mjs"
-    },
     "external": ["chalk", "dtrace-provider", "@linked-dependencies/external"],
   },
   "useTransformer": ({ build, transformer }) => {

__fixtures__/simple-project/verify.js

@@ -16,14 +16,14 @@ function main() {
 function verifyDirectoryStructure() {
   assertExists('package.json');
   assertExists('jest.config.json');
-  assertExists('globalSetup.mjs');
-  assertExists('globalTeardown.mjs');
-  assertExists('customReporter.mjs');
-  assertExists('src/entry1.test.mjs');
-  assertExists('src/entry2.test.mjs');
-  assertExists('_.._/linked-dependencies/bundled/reporters/default.mjs');
-  assertExists('bundled_externals/jest-environment-emit/node.mjs');
-  assertExists('bundled_externals/lodash/noop.mjs');
+  assertExists('globalSetup.js');
+  assertExists('globalTeardown.js');
+  assertExists('customReporter.js');
+  assertExists('src/entry1.test.js');
+  assertExists('src/entry2.test.js');
+  assertExists('_.._/linked-dependencies/bundled/reporters/default.js');
+  assertExists('bundled_externals/jest-environment-emit/node.js');
+  assertExists('bundled_externals/lodash/noop.js');
   assertDoesNotExist('node_modules');
   assertDoesNotExist('_.._/linked-dependencies/external');
 }
@@ -32,20 +32,20 @@ function verifyJestConfig() {
   const { coverageDirectory, globalSetup, reporters, setupFilesAfterEnv, testEnvironment, testMatch, testRunner, globalTeardown } = parseJSON('jest.config.json');
 
   assertEqual(coverageDirectory, '<rootDir>/coverage', 'coverageDirectory');
-  assertEqual(globalSetup, '<rootDir>/globalSetup.mjs', 'globalSetup');
+  assertEqual(globalSetup, '<rootDir>/globalSetup.js', 'globalSetup');
   assertEqual(reporters.length, 4, 'reporters length');
   assertEqual(reporters[0][0], 'default', 'reporters[0]');
-  assertEqual(reporters[1][0], '<rootDir>/_.._/linked-dependencies/bundled/reporters/default.mjs', 'reporters[1]');
+  assertEqual(reporters[1][0], '<rootDir>/_.._/linked-dependencies/bundled/reporters/default.js', 'reporters[1]');
   assertEqual(reporters[2][0], '@linked-dependencies/external/reporter', 'reporters[2]');
-  assertEqual(reporters[3][0], '<rootDir>/customReporter.mjs', 'reporters[3]');
+  assertEqual(reporters[3][0], '<rootDir>/customReporter.js', 'reporters[3]');
   assertEqual(setupFilesAfterEnv.length, 1, 'setupFilesAfterEnv.length');
-  assertEqual(setupFilesAfterEnv[0], '<rootDir>/bundled_externals/lodash/noop.mjs', 'setupFilesAfterEnv[0]');
-  assertEqual(testEnvironment, '<rootDir>/bundled_externals/jest-environment-emit/node.mjs', 'testEnvironment');
+  assertEqual(setupFilesAfterEnv[0], '<rootDir>/bundled_externals/lodash/noop.js', 'setupFilesAfterEnv[0]');
+  assertEqual(testEnvironment, '<rootDir>/bundled_externals/jest-environment-emit/node.js', 'testEnvironment');
   assertEqual(testMatch.length, 2, 'testMatch.length');
-  assertEqual(testMatch[0], '<rootDir>/src/entry1.test.mjs', 'testMatch[0]');
-  assertEqual(testMatch[1], '<rootDir>/src/entry2.test.mjs', 'testMatch[1]');
+  assertEqual(testMatch[0], '<rootDir>/src/entry1.test.js', 'testMatch[0]');
+  assertEqual(testMatch[1], '<rootDir>/src/entry2.test.js', 'testMatch[1]');
   assertEqual(testRunner, 'jest-circus/runner', 'testRunner');
-  assertEqual(globalTeardown, '<rootDir>/globalTeardown.mjs', 'globalTeardown');
+  assertEqual(globalTeardown, '<rootDir>/globalTeardown.js', 'globalTeardown');
 }
 
 function assertExists(fileName) {

index.mjs

@@ -2,7 +2,6 @@ import merge from 'lodash.merge';
 import { build as esbuild } from 'esbuild';
 
 import esbuildJest from './plugin.mjs';
-import {ESM_REQUIRE_SHIM} from "./utils/esm-require-shim.mjs";
 import {isBuiltinReporter} from "./utils/is-builtin-reporter.mjs";
 import {JEST_DEPENDENCIES} from "./utils/jest-dependencies.mjs";
 import {logger, optimizedLogger, optimizeTracing} from "./utils/logger.mjs";
@@ -89,10 +88,6 @@ export async function build(esbuildJestConfig = {}) {
     metafile: true,
     external: externalModules,
     outbase: rootDir,
-    banner: {
-      js: ESM_REQUIRE_SHIM,
-    },
-
     format: 'esm',
 
     entryPoints,

package.json

@@ -6,8 +6,7 @@
   "main": "index.mjs",
   "types": "index.d.mts",
   "bin": {
-    "esbuild-jest": "build.mjs",
-    "esbuild-jest-patch": "utils/patch-jest.mjs"
+    "esbuild-jest": "build.mjs"
   },
   "exports": {
     ".": "./index.mjs",
@@ -38,16 +37,16 @@
     "bunyan-debug-stream": "^3.1.0",
     "cosmiconfig": "^8.1.3",
     "find-up": "^7.0.0",
-    "lodash.merge": "^4.6.2",
     "import-from": "^4.0.0",
+    "lodash.merge": "^4.6.2",
     "resolve-from": "^5.0.0"
   },
   "peerDependencies": {
     "esbuild": ">=0.17.4"
   },
   "devDependencies": {
-    "@jest/types": "^29.6.3",
     "@jest/transform": "^29.6.3",
-    "esbuild": "^0.19.8"
+    "@jest/types": "^29.6.3",
+    "esbuild": "^0.21.4"
   }
 }

plugin.mjs

@@ -135,7 +135,8 @@ export default ({
           testEnvironment: mapFile(projectConfig.testEnvironment),
           testMatch: tests.map(mapFile),
           testRunner: mapFile(projectConfig.testRunner),
-          transform: {},
+          transform: undefined,
+          transformIgnorePatterns: undefined,
         };
 
         __JEST_CONFIG(logger, flattenedConfig);
@@ -157,18 +158,25 @@ export default ({
         const packageJson = packageMiddleware({
           name: 'bundled-tests',
           version: '0.0.0',
-          type: 'module',
           private: true,
           scripts: {
-            test: 'NODE_NO_WARNINGS=1 NODE_OPTIONS="--experimental-vm-modules" jest',
+            test: "NODE_OPTIONS='-r @babel/register' jest"
           },
           dependencies: {
+            "@babel/core": "^7.24.6",
+            "@babel/plugin-transform-modules-commonjs": "^7.24.6",
+            "@babel/register": "^7.24.6",
+
             ...externalDependencies,
           },
         });
 
         __PACKAGE_JSON(logger, packageJson);
         await writeFile(join(outdir, 'package.json'), JSON.stringify(packageJson, null, 2));
+        await writeFile(join(outdir, '.babelrc'), JSON.stringify({
+          "compact": false,
+          "plugins": ["@babel/plugin-transform-modules-commonjs"]
+        }, null, 2));
       });
     },
   };