Function stateExtensionExpectedToWork

test/typescript/enhancers.ts:196–270

()

  const reducer: Reducer<State> = null as any

  function stateExtensionExpectedToWork() {
    interface ExtraState {
      extraField: string
    }

    const enhancer: StoreEnhancer<{}, ExtraState> =
      createStore =>
      <S, A extends Action, PreloadedState>(
        reducer: Reducer<S, A, PreloadedState>,
        preloadedState?: PreloadedState | undefined
      ) => {
        const wrappedReducer: Reducer<
          S & ExtraState,
          A,
          PreloadedState & ExtraState
        > = (state, action) => {
          const newState = reducer(state, action)
          return {
            ...newState,
            extraField: 'extra'
          }
        }
        const wrappedPreloadedState = preloadedState
          ? {
              ...preloadedState,
              extraField: 'extra'
            }
          : undefined
        const store = createStore(wrappedReducer, wrappedPreloadedState)
        return {
          ...store,
          replaceReducer(nextReducer: Reducer<S, A>) {
            const nextWrappedReducer: Reducer<S & ExtraState, A> = (
              state,
              action
            ) => {
              const newState = nextReducer(state, action)
              return {
                ...newState,
                extraField: 'extra'
              }
            }
            return store.replaceReducer(nextWrappedReducer)
          }
        }
      }

    interface PartialState {
      someField?: 'string'
      test?: boolean
    }

    const initialReducer: Reducer<PartialState, Action> = () => ({
      someField: 'string'
    })
    const store = createStore<PartialState, Action, {}, ExtraState>(
      initialReducer,
      enhancer