@equinor/fusion-observable/src/__tests__/useObservableEffect.test.ts

WIP

import expect from 'expect';
import { renderHook, act } from '@testing-library/react-hooks';

import { useObservableEffect } from '../react/useObservableEffect';
import { useObservable } from '../react/useObservable';

import type { Reducer } from '../types';

const reducer: Reducer<
  { sum: number },
  { type: 'add'; payload: number } | { type: 'requestAdd'; payload: number }
> = (state, action) => {
  switch (action.type) {
    case 'add':
      return { ...state, sum: state.sum + action.payload };
  }
  return state;
};

describe('useObservableEffect', () => {
  it('effect', async () => {
    const { result, waitFor } = renderHook(() => {
      const subject = useObservable(reducer, { sum: 0 });
      useObservableEffect(subject, async (action) => {
        switch (action.type) {
          case 'requestAdd': {
            expect(action.payload).toBe(1);
            return { type: 'add', payload: action.payload } as const;
          }
        }
      });

      return subject;
    });

    act(() => {
      result.current.next({ type: 'requestAdd', payload: 1 });
      expect(result.current.value.sum).toBe(0);
    });

    await waitFor(() => {
      expect(result.current.value.sum).toBe(1);
    });
  });
});