Typescript act() got warning 'await' has no effect on the type of this expression. #1276

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1. mdjastrzebski commented on Jan 7, 2023

   

   mdjastrzebski

   on Jan 7, 2023

   Member

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   Looking at @types/react-test-render theirs act has following type:

   export function act(callback: () => Promise<VoidOrUndefinedOnly>): Promise<undefined>;
   

   As far as I understand the intention of async act is to allow for waiting for Promise returned by callback to resolve, but not to use it's return value in any way. We could actually tweak our typings to match @types/react-test-render ones.

   RTL does hits in the following way:

   /**
    * Simply calls ReactDOMTestUtils.act(cb)
    * If that's not available (older version of react) then it
    * simply calls the given callback immediately
    */
   export const act: typeof reactAct extends undefined
     ? (callback: () => void) => void
     : typeof reactAct

   @qaynam Would such solution satisfy your use case?

   👍React with 👍1Reacted by Archimedes Trajano
2. trajano commented on Jan 17, 2023

   

   trajano

   on Jan 17, 2023

   Last edited by trajano

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   I'm not sure how you'd declare it in the act.ts file but the generated act.d.ts file should have these two lines

   declare const act: (callback: () => void) => void;
   declare const act: (callback: () => Promise<VoidOrUndefinedOnly>): Promise<undefined>;
   

   You have to also ensure that the linters will allow

   await act(() => Promise.resolve());
   await act(async () => {});
   

   Since these are valid cases where the useEffect performs an async operation that needs to be waited on.

   👍React with 👍1Reacted by Maciej Jastrzebski
3. trajano commented on Jan 20, 2023

   

   trajano

   on Jan 20, 2023

   Last edited by trajano

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   I referenced this bug in https://stackoverflow.com/questions/64848604/how-to-resolve-act-in-useeffect/71949404#71949404 for more complete examples
4. mdjastrzebski

   closed this as completedin #1293on Jan 26, 2023