Function replaceReducerExtender

test/typescript/enhancers.ts:119–183

* replaceReducer with a store enhancer

()

 * replaceReducer with a store enhancer
 */
function replaceReducerExtender() {
  interface ExtraState {
    extraField: string
  }

  const enhancer: StoreEnhancer<{ method(): string }, ExtraState> =
    createStore =>
    <S, A extends Action, PreloadedState>(
      reducer: Reducer<S, A, PreloadedState>,
      preloadedState?: PreloadedState | undefined
    ) => {
      function wrapReducer<PreloadedStateToWrap>(
        reducer: Reducer<S, A, PreloadedStateToWrap>
      ): Reducer<S & ExtraState, A, PreloadedStateToWrap & ExtraState> {
        return (state, action) => {
          const newState = reducer(state, action)
          return {
            ...newState,
            extraField: class="st">'extra'
          }
        }
      }
      const wrappedPreloadedState = preloadedState
        ? {
            ...preloadedState,
            extraField: class="st">'extra'
          }
        : undefined
      const store = createStore(wrapReducer(reducer), wrappedPreloadedState)
      return {
        ...store,
        replaceReducer(nextReducer: Reducer<S, A>) {
          store.replaceReducer(wrapReducer(nextReducer))
        },
        method: () => class="st">'foo'
      }
    }

  interface PartialState {
    someField?: class="st">'string'
    test?: boolean
  }

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

  const newReducer = (state: PartialState = { test: true }, _: Action) => state

  store.replaceReducer(newReducer)
  store.getState().test
  store.getState().extraField