mirror of
https://github.com/oven-sh/bun
synced 2026-02-10 02:48:50 +00:00
de4a5a07b1
### What does this PR do? Fixes printing `import.meta.url` and others with `--bytecode`. Fixes #14954. Fixes printing `__toESM` when output module format is CJS and input module format is ESM. The key change is that `__toESM`'s `isNodeMode` parameter now depends on the **input module type** (whether the importing file uses ESM syntax like `import`/`export`) rather than the output format. This matches Node.js ESM behavior where importing CommonJS from `.mjs` files always wraps the entire `module.exports` object as the default export, ignoring `__esModule` markers. ### How did you verify your code works? Added comprehensive test suite in `test/bundler/bundler_cjs.test.ts` with **23 tests** covering: #### Core Behaviors: - ✅ Files using `import` syntax always get `isNodeMode=1`, which **ignores `__esModule`** markers and wraps the entire CJS module as default - ✅ This matches Node.js ESM semantics for importing CJS from `.mjs` files - ✅ Different CJS export patterns (`exports.x`, `module.exports = ...`, functions, primitives) - ✅ Named, default, and namespace (`import *`) imports - ✅ Different targets (node, browser, bun) - all behave the same - ✅ Different output formats (esm, cjs) - format doesn't affect the behavior - ✅ `.mjs` files re-exporting from `.cjs` - ✅ Deep re-export chains - ✅ Edge cases (non-boolean `__esModule`, `__esModule=false`, etc.) #### Test Results: - **With this PR's changes**: All 23 tests pass ✅ - **Without this PR (system bun)**: 22 pass, 1 fails (the one testing that `__esModule` is ignored with import syntax + CJS format) The failing test with system bun demonstrates the bug being fixed: currently, format=cjs with import syntax still respects `__esModule`, but it should ignore it (matching Node.js behavior). --------- Co-authored-by: Jarred Sumner <jarred@jarredsumner.com> Co-authored-by: Claude Bot <claude-bot@bun.sh>
495 lines
14 KiB
TypeScript
495 lines
14 KiB
TypeScript
import { describe } from "bun:test";
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import { itBundled } from "./expectBundled";
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// Tests for CommonJS <> ESM interop, specifically the __toESM helper behavior.
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//
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// The key insight from the code change:
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// - `input_module_type` is set based on the AST's exports_kind (whether the importing
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// file uses ESM syntax like import/export or CJS syntax like require/module.exports)
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// - When a file uses ESM syntax (import/export), isNodeMode = 1
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// - When a file uses CJS syntax (require), __toESM is not used at all
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//
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// This means:
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// - Any file using `import` will always get isNodeMode=1, which IGNORES __esModule
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// and always wraps the CJS module as the default export
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// - This matches Node.js ESM behavior where importing CJS from .mjs always wraps
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// the entire exports object as the default
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//
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// The __esModule marker is only respected in non-bundled scenarios or when using
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// actual CommonJS require() syntax.
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describe("bundler", () => {
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// ============================================================================
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// Tests with ESM syntax (import statements)
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// These all use isNodeMode=1, which IGNORES __esModule
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// ============================================================================
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// Test 1: import with __esModule marker - IGNORED
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itBundled("cjs/__toESM_import_syntax_with_esModule", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.__esModule = true;
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exports.default = { value: 'default export' };
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exports.named = 'named export';
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`,
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},
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run: {
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// With import syntax, isNodeMode=1, so __esModule is IGNORED
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// The entire CJS exports object is wrapped as default
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stdout: '{"__esModule":true,"default":{"value":"default export"},"named":"named export"}',
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},
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});
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// Test 2: import WITHOUT __esModule marker
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itBundled("cjs/__toESM_import_syntax_without_esModule", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.foo = 'foo';
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exports.bar = 'bar';
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`,
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},
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run: {
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// Same behavior - entire module wrapped as default
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stdout: '{"foo":"foo","bar":"bar"}',
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},
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});
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// Test 3: import with module.exports = function
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itBundled("cjs/__toESM_import_syntax_function", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(lib.name + ':' + lib());
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`,
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"/lib.cjs": /* js */ `
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module.exports = function myFunc() { return 'result'; };
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`,
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},
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run: {
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stdout: "myFunc:result",
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},
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});
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// Test 4: import with module.exports = primitive
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itBundled("cjs/__toESM_import_syntax_primitive", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(lib);
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`,
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"/lib.cjs": /* js */ `
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module.exports = 42;
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`,
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},
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run: {
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stdout: "42",
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},
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});
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// Test 5: import with named + default
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itBundled("cjs/__toESM_import_syntax_named_and_default", {
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files: {
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"/entry.js": /* js */ `
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import lib, { foo } from './lib.cjs';
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console.log(JSON.stringify({ default: lib, named: foo }));
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`,
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"/lib.cjs": /* js */ `
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exports.foo = 'foo value';
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exports.bar = 'bar value';
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`,
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},
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run: {
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stdout: '{"default":{"foo":"foo value","bar":"bar value"},"named":"foo value"}',
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},
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});
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// Test 6: Namespace import (import *)
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itBundled("cjs/__toESM_import_syntax_namespace", {
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files: {
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"/entry.js": /* js */ `
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import * as lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.foo = 'foo';
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exports.bar = 'bar';
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`,
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},
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run: {
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// Namespace import only gets the CJS exports as-is, no default wrapper
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stdout: '{"foo":"foo","bar":"bar"}',
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},
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});
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// ============================================================================
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// Tests with different targets
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// Target doesn't affect isNodeMode - it's based on syntax
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// ============================================================================
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// Test 7: target=node
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itBundled("cjs/__toESM_target_node", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.x = 1;
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exports.y = 2;
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`,
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},
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target: "node",
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run: {
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stdout: '{"x":1,"y":2}',
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},
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});
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// Test 8: target=browser
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itBundled("cjs/__toESM_target_browser", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.x = 1;
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exports.y = 2;
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`,
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},
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target: "browser",
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run: {
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stdout: '{"x":1,"y":2}',
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},
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});
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// Test 9: target=bun
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itBundled("cjs/__toESM_target_bun", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.x = 1;
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exports.y = 2;
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`,
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},
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target: "bun",
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run: {
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stdout: '{"x":1,"y":2}',
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},
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});
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// ============================================================================
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// Tests with different output formats
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// Output format doesn't affect isNodeMode either
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// ============================================================================
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// Test 10: format=esm
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itBundled("cjs/__toESM_format_esm", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.__esModule = true;
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exports.default = 'the default';
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exports.other = 'other';
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`,
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},
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format: "esm",
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run: {
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// __esModule ignored because we're using import syntax
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stdout: '{"__esModule":true,"default":"the default","other":"other"}',
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},
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});
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// Test 11: format=cjs with import syntax
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itBundled("cjs/__toESM_format_cjs_with_import", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.__esModule = true;
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exports.default = 'the default';
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exports.other = 'other';
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`,
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},
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format: "cjs",
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run: {
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// Still ignores __esModule because entry uses import syntax
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stdout: '{"__esModule":true,"default":"the default","other":"other"}',
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},
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});
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// ============================================================================
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// Tests for .mjs files re-exporting from .cjs
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// ============================================================================
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// Test 12: .mjs re-exporting default from CJS
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itBundled("cjs/__toESM_mjs_reexport", {
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files: {
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"/entry.js": /* js */ `
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import lib from './wrapper.mjs';
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console.log(JSON.stringify(lib));
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`,
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"/wrapper.mjs": /* js */ `
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export { default } from './lib.cjs';
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`,
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"/lib.cjs": /* js */ `
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exports.foo = 'foo';
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exports.bar = 'bar';
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`,
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},
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run: {
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stdout: '{"foo":"foo","bar":"bar"}',
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},
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});
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// Test 13: .mjs re-exporting with __esModule (still ignored)
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itBundled("cjs/__toESM_mjs_reexport_with_esModule", {
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files: {
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"/entry.js": /* js */ `
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import lib from './wrapper.mjs';
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console.log(JSON.stringify(lib));
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`,
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"/wrapper.mjs": /* js */ `
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export { default } from './lib.cjs';
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`,
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"/lib.cjs": /* js */ `
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exports.__esModule = true;
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exports.default = { value: 'from cjs' };
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exports.other = 'other';
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`,
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},
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run: {
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// __esModule ignored - entire module wrapped as default
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stdout: '{"__esModule":true,"default":{"value":"from cjs"},"other":"other"}',
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},
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});
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// Test 14: Deep re-export chain
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itBundled("cjs/__toESM_deep_reexport_chain", {
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files: {
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"/entry.js": /* js */ `
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import lib from './layer1.mjs';
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console.log(JSON.stringify(lib));
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`,
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"/layer1.mjs": /* js */ `
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export { default } from './layer2.mjs';
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`,
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"/layer2.mjs": /* js */ `
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export { default } from './lib.cjs';
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`,
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"/lib.cjs": /* js */ `
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exports.deep = 'value';
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`,
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},
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run: {
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stdout: '{"deep":"value"}',
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},
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});
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// Test 15: Re-export with rename
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itBundled("cjs/__toESM_reexport_with_rename", {
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files: {
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"/entry.js": /* js */ `
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import { myDefault } from './wrapper.mjs';
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console.log(JSON.stringify(myDefault));
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`,
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"/wrapper.mjs": /* js */ `
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export { default as myDefault } from './lib.cjs';
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`,
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"/lib.cjs": /* js */ `
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exports.x = 1;
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`,
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},
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run: {
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stdout: '{"x":1}',
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},
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});
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// ============================================================================
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// Edge cases
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// ============================================================================
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// Test 16: CJS with a property named "default" but no __esModule
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itBundled("cjs/__toESM_default_prop_no_esModule", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.default = 'I am a prop named default';
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exports.other = 'other';
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`,
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},
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run: {
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// Entire module wrapped, including the .default property
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stdout: '{"default":"I am a prop named default","other":"other"}',
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},
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});
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// Test 17: Mixed import styles
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itBundled("cjs/__toESM_mixed_import_styles", {
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files: {
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"/entry.js": /* js */ `
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import defaultExport from './lib.cjs';
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import { foo } from './lib.cjs';
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import * as namespace from './lib.cjs';
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console.log(JSON.stringify({
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default: defaultExport,
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named: foo,
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namespace: namespace
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}));
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`,
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"/lib.cjs": /* js */ `
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exports.foo = 'foo';
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exports.bar = 'bar';
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`,
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},
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run: {
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stdout:
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'{"default":{"foo":"foo","bar":"bar"},"named":"foo","namespace":{"default":{"foo":"foo","bar":"bar"},"foo":"foo","bar":"bar"}}',
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},
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});
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// Test 18: __esModule with non-true value
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itBundled("cjs/__toESM_esModule_non_true", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.__esModule = 'truthy';
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exports.default = { value: 'default' };
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exports.other = 'other';
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`,
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},
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run: {
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// Even if __esModule were respected, only `true` would work
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// But it's ignored anyway due to import syntax
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stdout: '{"__esModule":"truthy","default":{"value":"default"},"other":"other"}',
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},
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});
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// Test 19: __esModule = false
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itBundled("cjs/__toESM_esModule_false", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.__esModule = false;
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exports.default = { value: 'ignored' };
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exports.foo = 'foo';
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`,
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},
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run: {
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// Entire module wrapped as default (since we use import syntax)
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stdout: '{"__esModule":false,"default":{"value":"ignored"},"foo":"foo"}',
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},
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});
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// Test 20: module.exports with __esModule
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itBundled("cjs/__toESM_module_exports_with_esModule", {
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files: {
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"/entry.js": /* js */ `
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import lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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module.exports = {
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__esModule: true,
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default: { value: 'nested' },
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other: 'prop'
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};
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`,
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},
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run: {
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// __esModule is in the object but ignored due to import syntax
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stdout: '{"__esModule":true,"default":{"value":"nested"},"other":"prop"}',
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},
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});
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// Test 21: Input=ESM, output=CJS, importing CJS with __esModule and named imports
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// This test covers the specific fix for printing __toESM when output format is CJS
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// and input uses ESM syntax to import both default and named exports from CJS with __esModule
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itBundled("cjs/__toESM_input_esm_output_cjs_wrapper_print", {
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files: {
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"/entry.js": /* js */ `
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import lib, { named } from "./lib.cjs";
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console.log(JSON.stringify({ default: lib, named }));
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`,
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"/lib.cjs": /* js */ `
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exports.__esModule = true;
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exports.default = { value: "default" };
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exports.named = "named export";
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`,
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},
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format: "cjs",
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run: {
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// With the fix: ignores __esModule, wraps entire module as default
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// So default gets the whole exports object, named gets the named property
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stdout:
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'{"default":{"__esModule":true,"default":{"value":"default"},"named":"named export"},"named":"named export"}',
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},
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});
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// Test 22: Star import with __esModule
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itBundled("cjs/__toESM_star_import_with_esModule", {
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files: {
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"/entry.js": /* js */ `
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import * as lib from './lib.cjs';
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console.log(JSON.stringify(lib));
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`,
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"/lib.cjs": /* js */ `
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exports.__esModule = true;
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exports.default = 'default';
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exports.named = 'named';
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`,
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},
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run: {
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// Star import gets the exports as-is, no wrapper
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stdout: '{"named":"named","default":"default","__esModule":true}',
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},
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});
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// Test 23: Practical example - importing lodash-like library
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itBundled("cjs/__toESM_practical_lodash_style", {
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files: {
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"/entry.js": /* js */ `
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import _ from './lodash.cjs';
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import { map } from './lodash.cjs';
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console.log(JSON.stringify({
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hasMap: typeof _.map === 'function',
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same: _.map === map
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}));
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`,
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"/lodash.cjs": /* js */ `
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exports.map = function(arr, fn) { return arr.map(fn); };
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exports.filter = function(arr, fn) { return arr.filter(fn); };
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`,
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},
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run: {
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// Default gets entire module, named import gets specific function
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// Both reference the same function
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stdout: '{"hasMap":true,"same":true}',
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},
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});
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});
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