[Bug]: TypeScript 5.6 has a new behavior when handling ES6

Version

29.2.5

Steps to reproduce

The issue has been opened in jest but it seems to be a ts-jest issue: https://github.com/jestjs/jest/issues/15312

When using TypeScript and ES6 modules, it is common to transform these with ts-jest:

transform: {
    '\\.[tj]sx?$': [
        'ts-jest',
        {
            tsconfig: {
                outDir: './.ts-jest'
            }
        }
    ],
},
transformIgnorePatterns: [
    '/node_modules/(?!(ol|txml|geotiff|quick-lru|color-|rbush|earcut|pbf|quickselect))'
],

This for example will transform OpenLayers which is shipped as ES6 modules.

Since TypeScript 5.6 this does not work anymore, because TypeScript will interpret the type: module in OpenLayers itself and it will produce ES6 which jest won't parse.

Expected behavior

Someone should investigate this change of behavior and see what is to be done when TypeScript transpiler is used through its API.

Actual behavior

TypeScript produces ES6 code

Debug log

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    /home/mmom/src/rlayers/node_modules/ol/proj/proj4.js:40
    import Projection from './Projection.js';
    ^^^^^^

Additional context

The TypeScript changelog with a summary of the change: https://devblogs.microsoft.com/typescript/announcing-typescript-5-6/

An issue which discusses the change: https://github.com/microsoft/TypeScript/issues/59991

Environment

Does not depend on anything but TypeScript 5.6

kulshekhar / ts-jest

[Bug]: TypeScript 5.6 has a new behavior when handling ES6 #4561