Fix require()() in production bundle

src/plugins/fast-cjs-plugin.js

@@ -2,7 +2,7 @@ const CJS_KEYWORDS = /\b(module\.exports|exports)\b/;
 
 const ESM_KEYWORDS = /(\bimport\s*(\{|\s['"\w_$])|[\s;]export(\s+(default|const|var|let)[^\w$]|\s*\{))/;
 
-const HELPER = `function $$cjs_default$$(m){try{'default'in m||Object.defineProperty(m,'default',{configurable:true,value:m})}catch(e){}return m}`;
+const HELPER = `function $$cjs_default$$(m,i){for(i in m)if(i!='default')return m;return m.default||m}`;
 
 /**
  * Extremely loose and questionable (but fast) conversion from CJS to ESM.

test/fixtures.test.js

@@ -148,15 +148,15 @@ describe('fixtures', () => {
 			await getOutput(env, instance);
 
 			// import * as foo from './foo.cjs'
-			expect(await env.page.$eval('#cjs', el => JSON.parse(el.textContent || ''))).toEqual({
+			expect(await env.page.$eval('#cjs', el => JSON.parse(el.textContent || 'null'))).toEqual({
 				default: {
 					a: 'one',
 					b: 'two'
 				}
 			});
 
 			// import foo from './foo.cjs'
-			expect(await env.page.$eval('#cjsdefault', el => JSON.parse(el.textContent || ''))).toEqual({
+			expect(await env.page.$eval('#cjsdefault', el => JSON.parse(el.textContent || 'null'))).toEqual({
 				a: 'one',
 				b: 'two'
 			});
@@ -165,8 +165,45 @@ describe('fixtures', () => {
 			expect(await env.page.$eval('#cjsimport', el => JSON.parse(el.textContent || ''))).toEqual({
 				default: 'default export',
 				a: 1,
-				b: 2,
-				c: 3
+				b: 2
+			});
+
+			const imports = /** @type{object} */ (await env.page.evaluate(`import('/cjs-imports.cjs')`)).default;
+
+			// requiring a CJS module with (`exports.a=..`) exports should return its named exports:
+			expect(imports.namedCjs).toEqual({
+				a: 1,
+				b: 2
+			});
+			// requiring an ES module with only named exports should return its named exports:
+			expect(imports.namedEsm).toEqual({
+				a: 1,
+				b: 2
+			});
+
+			// requiring a CJS module with `module.exports=..` exports should return that default export:
+			expect(imports.defaultCjs).toEqual({
+				a: 1,
+				b: 2
+			});
+			// requiring an ES module with only a default export should return its default export:
+			expect(imports.defaultEsm).toEqual({
+				a: 1,
+				b: 2
+			});
+
+			// requiring an ES module with both named+default exports should return its default export:
+			expect(imports.mixedEsm).toEqual({
+				default: 'default export',
+				a: 1,
+				b: 2
+			});
+			// requiring a CJS module with transpiled named+default exports should return its faux ModuleRecord:
+			expect(imports.mixedCjs).toEqual({
+				__esModule: true,
+				default: 'default export',
+				a: 1,
+				b: 2
 			});
 		});
 	});

test/fixtures/commonjs/cjs-imports.cjs

@@ -0,0 +1,8 @@
+exports.namedCjs = require('./named.cjs');
+exports.namedEsm = require('./named.js');
+
+exports.defaultCjs = require('./default.cjs');
+exports.defaultEsm = require('./default.js');
+
+exports.mixedEsm = require('./mixed.js');
+exports.mixedCjs = require('./mixed.cjs');

test/fixtures/commonjs/default.cjs

@@ -0,0 +1 @@
+module.exports = { a: 1, b: 2 };

test/fixtures/commonjs/default.js

@@ -0,0 +1 @@
+export default { a: 1, b: 2 };

test/fixtures/commonjs/foo.cjs

@@ -1,8 +1,12 @@
-const other = require('./other.js');
+const other = require('./mixed.js');
 
 console.log(other);
 
-document.querySelector('#cjsimport').textContent = JSON.stringify(other);
+let collected = {};
+for (let i in other) collected[i] = other[i];
+collected.default = other.default;
+
+document.querySelector('#cjsimport').textContent = JSON.stringify(collected);
 
 exports.a = 'one';
 exports.b = 'two';

test/fixtures/commonjs/mixed.cjs

@@ -0,0 +1,13 @@
+// this is Babel's transpiled output of `mixed.js`
+
+exports.__esModule = true;
+exports.b = exports.a = exports.default = void 0;
+
+let _default = 'default export';
+exports.default = _default;
+
+const a = 1;
+exports.a = a;
+
+const b = 2;
+exports.b = b;

test/fixtures/commonjs/other.js → test/fixtures/commonjs/mixed.js

@@ -1,4 +1,3 @@
 export default 'default export';
 export const a = 1;
 export const b = 2;
-export const c = 3;

test/fixtures/commonjs/named.cjs

@@ -0,0 +1,2 @@
+exports.a = 1;
+exports.b = 2;

test/fixtures/commonjs/named.js

@@ -0,0 +1,2 @@
+export const a = 1;
+export const b = 2;