Jest - Cannot use import statement outside a module - using Rescript

Question

I am trying to run unit tests in a React project generated using react-scripts, in which I added ReScript support.

When I run the tests, however, I encountered an error in the transpiled javascript code.

Details of the error:

/Users/massimilianodacunzo/Projects/Elixir/test-project/apps/phoenix_react_web/assets/node_modules/bs-platform/lib/es6/array.js:3
import * as Curry from "./curry.js";
^^^^^^

SyntaxError: Cannot use import statement outside a module

  1 |
  2 |
> 3 | import * as $$Array from "../../../node_modules/bs-platform/lib/es6/array.js";
    | ^
  4 | import * as React from "react";
  5 |
  6 | function TestComponent(Props) {

  at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1350:14)
  at Object.<anonymous> (src/components/users/TestComponent.bs.js:3:1)

The components I am trying to test:

App.res

%%raw(`
import logo from './logo.svg';
import './App.css';
`)

@react.component
let make = () => {
    <div className="App">
        <TestComponent elements={["1", "2", "3"]} />
    </div>
}

TempComponent.res

@react.component
let make = (
    ~elements: array<string>
) => {
    <ul>
        {
            React.array(
                elements 
                |> Array.map(e => 
                    <li key={e}>{React.string(e)}</li>)
            )
        }
    </ul>
}

The generated TestComponent.bs.js

import * as $$Array from "../../../node_modules/bs-platform/lib/es6/array.js";
import * as React from "react";

function TestComponent(Props) {
  var elements = Props.elements;
  return React.createElement("ul", undefined, $$Array.map((function (e) {
                    return React.createElement("li", {
                                key: e
                              }, e);
                  }), elements));
}

var make = TestComponent;

export {
  make ,
  
}
/* react Not a pure module */

Is there any additional configuration I can add to the react-scripts test script?

Answer 1

Following the comment of glennsl, I followed the git issue, discovering that the configuration in my bsconfig.json file specified the package-specs module as es6. The test error didn't appear if I change the configuration to commonjs.

{
    ...
    "package-specs": {
      "module": "commonjs",
      "in-source": true
    }
    ...
}

Again, thanks to glennsl for pointing me in the right direction.