how to reset atom in unit test?

I know I can follow the doc here: https://docs.pmnd.rs/jotai/guides/resettable in my code to achieve this. But I’m writing unit tests in my project, which it appears that the atom value would be persisted somehow, but I think all the atom values used in different unit tests should not be the same.

my hook is defined below:

export const stepAtom = atom(0);

export function useOnBoardingService() {
  const { width } = useWindowDimensions();
  const [currentIndex, updateStep] = useAtom(stepAtom);

  const slidePrev = useCallback(() => {
    if (currentIndex !== 0) {
      const step = currentIndex - 1;
      updateStep(step);
    }
  }, [currentIndex, updateStep]);

  const slideNext = useCallback(() => {
    if (currentIndex !== 3) {
      const step = currentIndex + 1;
      updateStep(step);
    }
  }, [currentIndex, updateStep]);

  return {
    slidePrev,
    slideNext,
  };
}

and my unit test is below:

import { renderHook, act } from '@testing-library/react-hooks';
import { useAtomValue } from 'jotai/utils';
import { useOnBoardingService, stepAtom } from './useOnBoardingService';

test('should useOnBoardingService', () => {
  const { result } = renderHook(() => useOnBoardingService());
  expect(typeof result.current.slidePrev).toBe('function');
});

test('should step be 1', () => {
  const { result } = renderHook(() => useOnBoardingService());
  const { result: stepResult } = renderHook(() => useAtomValue(stepAtom));

  expect(stepResult.current).toBe(0);

  act(() => {
    result.current.slideNext();
  });

  expect(stepResult.current).toBe(1);
});

test('should step be 1 too', () => {
  const { result } = renderHook(() => useOnBoardingService());
  const { result: stepResult } = renderHook(() => useAtomValue(stepAtom));

  // I want this to be 0 but it actually is 1 because atom value changed after the above test executed
  expect(stepResult.current).toBe(0); 

  act(() => {
    result.current.slideNext();
  });

  // actual value would be 2
  expect(stepResult.current).toBe(1);
});

[dai-shi]

atomWithReset is not primarily for testing. Provider is. jotai is based on react context and to isolate state within memory, we need to use <Provider>.

According to https://react-hooks-testing-library.com/usage/advanced-hooks#context

import { Provider } from 'jotai'

const wrapper = ({ children }) => <Provider>{children}</Provider>

This may help.

[dai-shi]

I’d personally do that even with useState. It’s more about how you organize your code in React in general. The library is rather unopinionated about the code structure. Happy to see someone come up with best practices.