fix replaceReducer, so that it infers types, fix example test

reduxjs · Aug 29, 2019 · 8ca8290 · 8ca8290
1 parent 8ed803d
commit 8ca8290
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Showing 2 changed files with 33 additions and 8 deletions.
diff --git a/index.d.ts b/index.d.ts
@@ -342,7 +342,7 @@ export interface Store<
    *
    * @param nextReducer The reducer for the store to use instead.
    */
-  replaceReducer<NewState = S, NewActions extends A = A>(
+  replaceReducer<NewState, NewActions extends Action>(
     nextReducer: Reducer<NewState, NewActions>
   ): Store<NewState & StateExt, NewActions, StateExt, Ext> & Ext
 

diff --git a/test/typescript/enhancers.ts b/test/typescript/enhancers.ts
@@ -1,4 +1,4 @@
-import { PreloadedState, Store } from '../../index'
+import { PreloadedState } from '../../index'
 import { StoreEnhancer, Action, AnyAction, Reducer, createStore } from 'redux'
 
 interface State {
@@ -125,18 +125,43 @@ function mhelmersonExample() {
       A extends Action = AnyAction
     >(
       reducer: Reducer<S, A>,
-      preloadedState?: PreloadedState<S>
+      preloadedState?: any
     ) => {
-      const wrappedReducer: Reducer<S & ExtraState, A> = null as any
-      const wrappedPreloadedState: PreloadedState<S & ExtraState> = null as any
+      const wrappedReducer = (state: S & ExtraState | undefined, action: A) => {
+        const newState = reducer(state, action)
+        return {
+          ...newState,
+          extraField: 'extra'
+        } as S & ExtraState
+      }
+      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> = null as any
+        replaceReducer<NS, NA extends Action = AnyAction>(
+          nextReducer: (
+            state: NS & ExtraState | undefined,
+            action: NA
+          ) => NS & ExtraState
+        ) {
+          const nextWrappedReducer: Reducer<NS & ExtraState, NA> = (
+            state,
+            action
+          ) => {
+            const newState = nextReducer(state, action)
+            return {
+              ...newState,
+              extraField: 'extra'
+            }
+          }
           return store.replaceReducer(nextWrappedReducer)
         }
-      } as Store<S & ExtraState, A, ExtraState>
+      }
     }
 
     const store = createStore(reducer, enhancer)