Merge pull request #3475 from reduxjs/action-creator-without-payload-fix

Author: markerikson

packages/toolkit/src/createSlice.ts

@@ -353,6 +353,9 @@ interface AsyncThunkCreator<
 }
 
 export interface ReducerCreators<State> {
+  reducer(
+    caseReducer: CaseReducer<State, PayloadAction>
+  ): CaseReducerDefinition<State, PayloadAction>
   reducer<Payload>(
     caseReducer: CaseReducer<State, PayloadAction<Payload>>
   ): CaseReducerDefinition<State, PayloadAction<Payload>>
@@ -746,7 +749,7 @@ function buildReducerCreators<State>(): ReducerCreators<State> {
   }
   asyncThunk.withTypes = () => asyncThunk
   return {
-    reducer(caseReducer) {
+    reducer(caseReducer: CaseReducer<State, any>) {
       return Object.assign(
         {
           // hack so the wrapping function has the same name as the original

packages/toolkit/src/tests/createSlice.typetest.ts

@@ -599,9 +599,20 @@ const value = actionCreators.anyKey
       }>()
 
       return {
-        normalReducer: create.reducer<string>((state, action) => {
+        normalReducer: create.reducer(
+          (state, action: PayloadAction<string>) => {
+            expectType<TestState>(state)
+            expectType<string>(action.payload)
+          }
+        ),
+        optionalReducer: create.reducer(
+          (state, action: PayloadAction<string | undefined>) => {
+            expectType<TestState>(state)
+            expectType<string | undefined>(action.payload)
+          }
+        ),
+        noActionReducer: create.reducer((state) => {
           expectType<TestState>(state)
-          expectType<string>(action.payload)
         }),
         preparedReducer: create.preparedReducer(
           (payload: string) => ({
@@ -707,6 +718,23 @@ const value = actionCreators.anyKey
   type StoreDispatch = typeof store.dispatch
 
   expectType<PayloadActionCreator<string>>(slice.actions.normalReducer)
+  slice.actions.normalReducer('')
+  // @ts-expect-error
+  slice.actions.normalReducer()
+  // @ts-expect-error
+  slice.actions.normalReducer(0)
+  expectType<ActionCreatorWithOptionalPayload<string | undefined>>(
+    slice.actions.optionalReducer
+  )
+  slice.actions.optionalReducer()
+  slice.actions.optionalReducer('')
+  // @ts-expect-error
+  slice.actions.optionalReducer(0)
+
+  expectType<ActionCreatorWithoutPayload>(slice.actions.noActionReducer)
+  slice.actions.noActionReducer()
+  // @ts-expect-error
+  slice.actions.noActionReducer('')
   expectType<
     ActionCreatorWithPreparedPayload<
       [string],