Esbuild generating strange output, including a SyntaxError

[charliegroll]

---

BUG REPORT INFORMATION

While working on #625, I created a test that attempts to zip and use 3 functions; one with an import and export, one with just an import, and one with just an export.

tests/fixtures/local-require-esm
├── function
│   ├── file.js
│   └── function.js
├── function-export-only
│   └── index.js
└── function-import-only
    └── index.js

The branch: https://github.com/netlify/zip-it-and-ship-it/tree/cg2/EsBuildBundlingError

The comparison: https://github.com/netlify/zip-it-and-ship-it/compare/cg2/EsBuildBundlingError?expand=1

There are 2 commits:

• e485a30 introduces a single test which passes
• 854f7f1 adds the export-/import-only scenarios, which cause a SyntaxError

Isolated, the test has 2 failures. The first is expected, which is just saying Cannot use import statement outside a module.

The second is more interesting:

Rejected promise returned by test. Reason:

  SyntaxError {
    message: 'Unexpected token \'}\'',
  }

  › SyntaxError: Unexpected token '}'
  › Object.<anonymous> (/private/var/folders/1y/ncw647pd6vn79fg43s98wjrm0000gn/T/zip-it-test-bundler-esbuild-74878-s2RkNMGo46Ip/function-export-only.js:1:18)

because the main generated file contains all 3 functions and has an extra curly brace on line 11:

- What is the expected behavior?

esbuild should generate valid js output, and I would've assumed it would create 3 files for the 3 functions instead of clobbering them into 1 file that 3 functions merely import.

- Please mention your node.js, and operating system version.
Node 16.7.0
OS X 11.4

[charliegroll]

The reason this happens isn't a problem with esbuild! It's a problem with our test tooling.

every test makes use of requireExtractedFiles to open the generated zip (via unzipFiles) and require the files inside it.

in that fixture, you have two functions whose entry file is named index.js, so there will be an index.js inside each of the corresponding zip archives.

when the test suite unzips them, all the files will be placed in the temporary out directory, so it'll write the contents of both index.js files to the same index.js destination, leaving you with a mashed up index.js in the end

you can fix the test by naming the files function-export-only.js and function-import-only.js, instead of index.js

- @eduardoboucas

I've confirmed this works with 136daea in #625

Thanks @eduardoboucas for the investigation!