Testing useWorker #41
Description
Since they are plans to add new features (#36) I started to work in adding some tests for the hook. I initially setup Jest with react-hooks-testing-library. But found that Jest (which uses jsdom) does not have an implementation for URL.createObjectURL nor Web Workers.
So I had to dig a bit on the internet 🌈to find potential workarounds, and it seems that they're two approaches to test workers (afaik) that we can use.
Options
- Test with karma on headless chrome, this approach is used by comlink which is a wrapper for Web Workers. I did try this and it worked nicely, the one downside I see is the tooling (needs a preprocessor like webpack with babel to bundle everything for the test, as it's going to be tested in a browser) but at the end they're just devDependencies so it will not affect bundle size.
- Mock the Web Worker with something like jsdom-worker (although looks like is not actively maintained). This package also comes with a
URL.createObjectURLmock :).
Imo, I prefer karma since it will provide reliable behavior for the tests. What do you guys think? 😄
For reference, this is the test I tried with Karma:
import React from "react";
import { useWorker } from "../dist/index";
import { renderHook } from "@testing-library/react-hooks";
it("Basic Test", async () => {
const sum = (a, b) => a + b;
const { result } = renderHook(() => useWorker(sum));
const [sumWorker] = result.current;
const res = await sumWorker(1, 2);
assert.equal(res, 3);
});