Revert createReducer() type change

Things are fixed in v1.10.5.

Author: denisw

package-lock.json

@@ -47,7 +47,7 @@
     "index.d.ts"
   ],
   "dependencies": {
-    "immer": "^1.10.3",
+    "immer": "^1.10.5",
     "redux": "^4.0.0",
     "redux-devtools-extension": "^2.13.7",
     "redux-immutable-state-invariant": "^2.1.0",

package.json

@@ -1,4 +1,4 @@
-import createNextState, { Draft, Immutable } from 'immer'
+import createNextState, { Draft } from 'immer'
 import { AnyAction, Action, Reducer } from 'redux'
 
 /**
@@ -44,10 +44,10 @@ export interface CaseReducersMapObject<S = any, A extends Action = AnyAction> {
  *   case redeucers.
  */
 export function createReducer<S = any, A extends Action = AnyAction>(
-  initialState: Immutable<S>,
+  initialState: S,
   actionsMap: CaseReducersMapObject<S, A>
-): Reducer<Immutable<S>, A> {
-  return function(state = initialState, action): Immutable<S> {
+): Reducer<S, A> {
+  return function(state = initialState, action): S {
     // @ts-ignore createNextState() produces an Immutable<Draft<S>> rather
     // than an Immutable<S>, and TypeScript cannot find out how to reconcile
     // these two types.

src/createReducer.ts

@@ -1,4 +1,3 @@
-import { Immutable } from 'immer'
 import { Action, AnyAction, ActionCreator, Reducer } from 'redux'
 import { createAction, PayloadAction } from './createAction'
 import { createReducer, CaseReducersMapObject } from './createReducer'
@@ -51,7 +50,7 @@ export interface CreateSliceOptions<
   /**
    * The initial state to be returned by the slice reducer.
    */
-  initialState: Immutable<S>
+  initialState: S
 
   /**
    * A mapping from action types to action-type-specific *case reducer*
@@ -79,7 +78,7 @@ export function createSlice<
   CR extends CaseReducersMapObject<S, A> = CaseReducersMapObject<S, A>
 >(
   options: CreateSliceOptions<S, A, CR>
-): Slice<Immutable<S>, A, Extract<keyof CR, string>> {
+): Slice<S, A, Extract<keyof CR, string>> {
   const { slice = '', initialState } = options
   const reducers = options.reducers || {}
   const actionKeys = Object.keys(reducers)

src/createSlice.ts

@@ -58,25 +58,14 @@ import { AnyAction, createReducer, Reducer } from 'redux-starter-kit'
 }
 
 /*
- * Test: createReducer() reducers are typed to return readonly states.
+ * Test: createReducer() ensures state type is mutable within a case reducer.
  */
 {
-  const initialCounters = {
-    a: 0,
-    b: 0
-  }
+  const initialState: { readonly counter: number } = { counter: 0 }
 
-  const reducer = createReducer(initialCounters, {
-    incrementA: state => {
-      state.a += 1
-    },
-    incrementB: state => {
-      state.b += 1
+  createReducer(initialState, {
+    increment: state => {
+      state.counter += 1
     }
   })
-
-  const newCounters = reducer(initialCounters, { type: 'incrementA' })
-
-  // typings:expect-error
-  newCounters.a++
 }