loading svelte packages from node_modules

[darkship]

Not every Svelte packages are providing CommonJSmodules needed by Jest.

Examples:
svelte-select: provides es, mjs modules and the svelte component
svelte-calendar: provides only the svelte component.

Is there something I can do to tell jest that it has to look for the svelte component when it comes from node_modules?

import Select from 'svelte-select';
import * as CommonJSSelect from 'svelte-select';
const SelectComponent = Select || CommonJSSelect; // issues with jest, needs CommonJS

[mihar-22]

Hey @darkship you can use jest-svelte-resolver to make Jest resolve the .svelte files.

[darkship]

I tried it. It breaks the handling of components with svelte-jester. And I don't find the related github page of this package

[basarbk]

Hi @darkship ,
You can use "transformIgnorePatterns" configuration of jest. By default the node_modules folder is ignored. So by setting it as follows

  "transformIgnorePatterns": [
    "node_modules/(?!(svelte-select|svelte-calendar)/)"
  ],

the folders "svelte-select" and "svelte-calendar" in the node_modules, will be transformed based on the transform config.

[sebastianrothe]

This should be fixed with Jest 27+ and Sveltekit requiring ESM.