Cannot find module 'postal-mime' from [PATH]

[abhiaiyer91]

Hi, I am running some functions that use PostalMime. All is well in my NextJS serverless environment but when I run the tests via Jest I get the following error:

Cannot find module 'postal-mime' from '/path/to/function'

What would be the remedy to this?

[andris9]

This is some kind of loader issue. PostalMime is a standard ESM module.

[ValentinH]

I faced the same issue.
We had issue in the past with ESM only packages like query-string and we had to add it to the transformIgnorePatterns config:

  transformIgnorePatterns: [
    // query-string
    // https://github.com/sindresorhus/query-string/issues/366#issuecomment-1580854027
    'node_modules/(?!(query-string)/)',
  ],

However, with postal-mime it doesn't work.
If I manually update the package.json to be:

"exports": {
    "require": "./src/postal-mime.js",
    "import": "./src/postal-mime.js",
    "types": "./postal-mime.d.ts"
},

or

"exports": {
    "default": "./src/postal-mime.js",
    "types": "./postal-mime.d.ts"
},

then it works.

Not sure of the impact of doing this though 🙈