Use regenerator instead of async-to-promises to transpile async functions

package.json

@@ -44,8 +44,6 @@
     "@babel/core": "^7.4.4",
     "@babel/helper-module-imports": "^7.0.0",
     "@babel/plugin-proposal-class-properties": "^7.4.4",
-    "@babel/plugin-transform-regenerator": "^7.4.5",
-    "@babel/polyfill": "^7.4.4",
     "@babel/preset-env": "^7.11.0",
     "@rollup/plugin-commonjs": "^11.0.0",
     "@rollup/plugin-json": "^4.0.0",
@@ -60,7 +58,7 @@
     "babel-plugin-annotate-pure-calls": "^0.4.0",
     "babel-plugin-dev-expression": "^0.2.1",
     "babel-plugin-macros": "^2.6.1",
-    "babel-plugin-transform-async-to-promises": "^0.8.14",
+    "babel-plugin-polyfill-regenerator": "^0.0.4",
     "babel-plugin-transform-rename-import": "^2.3.0",
     "babel-traverse": "^6.26.0",
     "babylon": "^6.18.0",
@@ -86,6 +84,7 @@
     "pascal-case": "^3.1.1",
     "prettier": "^1.19.1",
     "progress-estimator": "^0.2.2",
+    "regenerator-runtime": "^0.13.7",
     "rollup": "^1.32.1",
     "rollup-plugin-babel": "^4.3.2",
     "rollup-plugin-sourcemaps": "^0.5.0",
@@ -100,7 +99,6 @@
     "typescript": "^3.7.3"
   },
   "devDependencies": {
-    "@babel/plugin-transform-runtime": "^7.6.0",
     "@types/eslint": "^6.1.2",
     "@types/fs-extra": "^8.0.0",
     "@types/node": "^13.1.0",

src/babelPluginTsdx.ts

@@ -75,18 +75,14 @@ export const babelPluginTsdx = babelPlugin.custom(() => ({
           replacements,
         },
         {
-          name: 'babel-plugin-transform-async-to-promises',
-          inlineHelpers: true,
-          externalHelpers: true,
+          name: 'babel-plugin-polyfill-regenerator',
+          // don't pollute global env as this is being used in a library
+          method: 'usage-pure',
         },
         {
           name: '@babel/plugin-proposal-class-properties',
           loose: true,
         },
-        {
-          name: '@babel/plugin-transform-regenerator',
-          async: false,
-        },
         isTruthy(customOptions.extractErrors) && {
           name: './errors/transformErrorMessages',
         },
@@ -114,10 +110,6 @@ export const babelPluginTsdx = babelPlugin.custom(() => ({
             presetEnv.options,
             {
               modules: false,
-              exclude: merge(
-                ['transform-async-to-generator', 'transform-regenerator'],
-                (presetEnv.options && presetEnv.options.exclude) || []
-              ),
             }
           ),
         ],
@@ -133,7 +125,6 @@ export const babelPluginTsdx = babelPlugin.custom(() => ({
           targets: customOptions.targets,
           modules: false,
           loose: true,
-          exclude: ['transform-async-to-generator', 'transform-regenerator'],
         },
       ]);
 

src/createRollupConfig.ts

@@ -60,9 +60,11 @@ export async function createRollupConfig(
     input: opts.input,
     // Tell Rollup which packages to ignore
     external: (id: string) => {
-      if (id === 'babel-plugin-transform-async-to-promises/helpers') {
+      // bundle in polyfills as TSDX can't (yet) ensure they're installed as deps
+      if (id.startsWith('regenerator-runtime')) {
         return false;
       }
+
       return external(id);
     },
     // Rollup has treeshaking by default, but we can optimize it further...
@@ -118,11 +120,14 @@ export async function createRollupConfig(
         // defaults + .jsx
         extensions: ['.mjs', '.js', '.jsx', '.json', '.node'],
       }),
-      opts.format === 'umd' &&
-        commonjs({
-          // use a regex to make sure to include eventual hoisted packages
-          include: /\/node_modules\//,
-        }),
+      // all bundled external modules need to be converted from CJS to ESM
+      commonjs({
+        // use a regex to make sure to include eventual hoisted packages
+        include:
+          opts.format === 'umd'
+            ? /\/node_modules\//
+            : /\/regenerator-runtime\//,
+      }),
       json(),
       {
         // Custom plugin that removes shebang from code because newer

test/e2e/fixtures/build-default/src/index.ts

@@ -3,6 +3,9 @@ import './syntax/optional-chaining';
 
 import './syntax/jsx-import/JSX-import-JSX';
 
+import './syntax/async';
+export { testGenerator } from './syntax/generator';
+
 export { foo } from './foo';
 
 export const sum = (a: number, b: number) => {

test/e2e/fixtures/build-default/src/syntax/async.ts

@@ -0,0 +1,6 @@
+// regression test for async/await
+// code inspired by https://github.com/formium/tsdx/issues/869
+(async () => {
+  await Promise.resolve();
+  console.log('a side effect to make sure this is output');
+})();

test/integration/fixtures/build-withBabel/src/generator.ts → test/e2e/fixtures/build-default/src/syntax/generator.ts

@@ -1,3 +1,4 @@
+// regression test for generators
 export function* testGenerator() {
   return yield 'blah';
 }

test/e2e/tsdx-build-default.test.ts

@@ -1,7 +1,7 @@
 import * as shell from 'shelljs';
 
 import * as util from '../utils/fixture';
-import { execWithCache } from '../utils/shell';
+import { execWithCache, grep } from '../utils/shell';
 
 shell.config.silent = false;
 
@@ -51,6 +51,22 @@ describe('tsdx build :: zero-config defaults', () => {
     expect(output.code).toBe(0);
   });
 
+  it('should bundle regeneratorRuntime', () => {
+    const output = execWithCache('node ../dist/index.js build');
+    expect(output.code).toBe(0);
+
+    const matched = grep(/regeneratorRuntime = r/, ['dist/build-default.*.js']);
+    expect(matched).toBeTruthy();
+  });
+
+  it('should not bundle regeneratorRuntime when targeting Node', () => {
+    const output = execWithCache('node ../dist/index.js build --target node');
+    expect(output.code).toBe(0);
+
+    const matched = grep(/regeneratorRuntime = r/, ['dist/build-default.*.js']);
+    expect(matched).toBeFalsy();
+  });
+
   it('should clean the dist directory before rebuilding', () => {
     let output = execWithCache('node ../dist/index.js build');
     expect(output.code).toBe(0);

test/integration/fixtures/build-withBabel/.babelrc.js

@@ -2,8 +2,5 @@ module.exports = {
   presets: [
     // ensure Babel presets are merged and applied
     './test-babel-preset'
-  ],
-  plugins: [
-   ['@babel/plugin-transform-runtime', { helpers: false }],
   ]
 }

test/integration/fixtures/build-withBabel/src/index.ts

@@ -1,7 +1,5 @@
 export { Title } from './styled';
 
-export { testGenerator } from './generator';
-
 export const sum = (a: number, b: number) => {
   if ('development' === process.env.NODE_ENV) {
     console.log('fuck');

test/integration/tsdx-build-withBabel.test.ts

@@ -37,16 +37,6 @@ describe('integration :: tsdx build :: .babelrc.js', () => {
     expect(matched).toBeFalsy();
   });
 
-  it('should add an import of regeneratorRuntime', () => {
-    const output = execWithCache('node ../dist/index.js build');
-    expect(output.code).toBe(0);
-
-    const matched = grep(/@babel\/runtime\/regenerator/, [
-      'dist/build-withbabel.*.js',
-    ]);
-    expect(matched).toBeTruthy();
-  });
-
   it('should merge and apply presets', () => {
     const output = execWithCache('node ../dist/index.js build');
     expect(output.code).toBe(0);