Ava: Please do not recommend browser-env for browser testing

[domenic]

That package uses an explicitly unsupported jsdom anti-pattern and is very bad practice to recommend to consumers of ava.

[sindresorhus]

// @lukechilds

[lukechilds]

Regarding the two main points in that link, the docs do recommend only requiring the properties needed to prevent unnecessary globals and I don't think attaching them to global is as big of an issue as it normally would be due to the way AVA runs each test file in a separate process.

That said, I'm aware this isn't the cleanest solution in the world. To match the example I think we would have create a new jsdom instance inside every test because they all run async in AVA. It would also require that the module is first built for the browser so it can be injected in via a script tag.

I feel like the current solution gets you 99% of the way there in one function call and makes sense until AVA is running natively in the browser.

[domenic]

It would also require that the module is first built for the browser so it can be injected in via a script tag.

Yes. That is exactly the point! You need to test the same scenario as you will be deploying to your users.

[lukechilds]

I understand your point. I'm not quite sure how you would get the react example working in the current recipe. It loads extra modules for testing which would also need to be built for browsers.

I don't disagree with what you're saying, I still think this method is ok to easily test simple modules, but maybe it would be better to not recommend browser-env because more complex modules may end up passing tests by using Node.js functionality that wouldn't be available in a sandboxed jsdom environment.

[Akkuma]

To defend browser-env. I feel it does exactly what it should/could do. I'm using it for testing a browser web extension, which is inherently even more difficult to test. I already have browser automation tests to guarantee if X is done Y happens. However, I can see the need for it to go away once AVA supports running in a real browser.

[domenic]

I understand that some people want to abuse jsdom in ways it's not meant to be used and that are not supported. I especially understand if the author of a module geared around doing so wants to do that. But I don't think a widely-used test-runner such as ava should be recommending such practices.

[lukechilds]

I can see your concern. Maybe we should add a disclaimer in the browser recipe that makes it clear that this is not recommended and is a temporary workaround until AVA is supported in the browser.

I've just added a disclaimer to the browser-env repo linking to the above wiki page: https://github.com/lukechilds/browser-env

[novemberborn]

Assuming your browser code runs under Node.js without compilation then IMHO browser-env is still a good way of getting enough globals and DOM in place to exercise that code. AVA at least isolates different test files from each other. Our current browser testing recipe focuses on these kinds of tests.

Ideally though you'd compile your browser code first and test that in a less "hybrid franken-environment".

I'd like to see the recipe address this distinction. I'm curious how people exercise their browser code though, there may be quite a habit of running it directly in Node.js rather than properly isolated in jsdom.

[novemberborn]

Addressed with #1355.