@vitest/web-worker: How to pass File object to SharedWorker?

[heidemn-faro]

Hi there,

In our vitest tests, I'm trying to get a File object into our SharedWorker that is responsible for uploading.
The file object is sent via this.#worker?.port.postMessage(message);
...where message is a plain object containing a File and some parameters.

What I see is that the SharedWorker doesn't well receive the File object, but instead an empty object with file instanceof File being false and file.constructor.name === "Object".
The code runs fine in the browser, there I can properly receive it and file instanceof File is true.

I already tried to mock structuredClone in the tests, but seems like it is not called.

Any idea how to get it working?

Libraries that we're using that might be relevant:

    "@testing-library/dom": "^10.4.0",
    "@testing-library/jest-dom": "^6.3.3",
    "@testing-library/react": "^16.0.1",
    "@vitest/coverage-v8": "^2.1.5",
    "@vitest/web-worker": "^2.1.9",
    "jsdom": "^25.0.1",
    "vite": "^5.4.10",
    "vite-plugin-eslint": "^1.8.1",
    "vite-plugin-handlebars": "^2.0.0",
    "vite-plugin-html": "^3.2.2",
    "vite-tsconfig-paths": "^4.3.2",
    "vitest": "^2.1.5"