Disabling the warning in 16.8

[aravindet]

Hi Sunil! 😄

I know this is a somewhat annoying ask, but is there a good way to suppress the act() warning until 16.9 is released?

(The code I'm testing ends up creating a chain of promises, which Jest's fake timers won't run synchronously until this is merged.)

[danielkcz]

Why don't you use 16.9 alpha version? The async act should be able to take care of chain of promises.

[aravindet]

I definitely agree that 16.9 would have been ideal. There's of course some circumstances specific to my project (although it can't be that rare) that factors in:

• This needs to go into production, and the app in question has a lot of paying users so using the alpha is not really feasible.
• Our CI is set up to fail if build/test produces warnings to console. I can't merge my otherwise working feature unless I can suppress this warning. 😢
• The thing I'm working on involves some third-party libraries that schedule asynchronous tasks in a way that cannot really be trapped by Jest timer mocks.

[danielkcz]

This needs to go into production, and the app in question has a lot of paying users so using the alpha is not really feasible.

I would say this is more of the scarecrow that a real issue. React is very stable and "alpha" doesn't mean "it's broken", but "there are some new things we want users to check out before rolling out" instead. I would even say it's intentional to test these releases in production. Imagine there is a bug that gets revealed only in your code. The "stable" 16.9 comes out, you will use it and bam, bug hits you anyway.

Furthermore, I believe that particular release is focused on act only, so it should be pretty safe regarding the actual production code. Well, if you are unwilling to put forward some trust, I am afraid you have to wait.

Alternatively, you can try jest --silent which should hide pretty much anything including act warnings. Or figure out some other way on suppressing console output in tests, it's not that hard really, eg. jest-mock-console.

[aravindet]

So is there no way to just disable the "You've caused a rerender outside of act()" warning with no other effects?

[danielkcz]

AFAIK there is no such thing as it would be too tempting to just disable instead of fixing the situation :)

[threepointone]

@aravindet does jest-mock-console not unblock you? you can use it in your warning tests, and assert that only the act warning fires (and then remove it once 16.9 is released)

[aravindet]

@threepointone that might work, thanks!

They are already hijacking the console to add the "fail CI on output" behaviour, but I think I can double-hijack it during my tests 👍