From 762f161dea57dd2979a7ae399acd6de70b2e91f9 Mon Sep 17 00:00:00 2001
From: Thibault Gouala <thibault.gouala@gmail.com>
Date: Sun, 16 Feb 2020 18:20:26 +0100
Subject: [PATCH] strongly type slice name (#354)

* strongly type slice name

* move new generic to the end and default it to string
---
 etc/redux-toolkit.api.md                 | 10 ++---
 src/createSlice.ts                       | 21 ++++++-----
 type-tests/files/createSlice.typetest.ts | 47 ++++++++++++++++++++----
 3 files changed, 57 insertions(+), 21 deletions(-)

diff --git a/etc/redux-toolkit.api.md b/etc/redux-toolkit.api.md
index fa63fde73..f435fb8e0 100644
--- a/etc/redux-toolkit.api.md
+++ b/etc/redux-toolkit.api.md
@@ -112,13 +112,13 @@ export { createSelector }
 export function createSerializableStateInvariantMiddleware(options?: SerializableStateInvariantMiddlewareOptions): Middleware;
 
 // @public
-export function createSlice<State, CaseReducers extends SliceCaseReducers<State>>(options: CreateSliceOptions<State, CaseReducers>): Slice<State, CaseReducers>;
+export function createSlice<State, CaseReducers extends SliceCaseReducers<State>, Name extends string = string>(options: CreateSliceOptions<State, CaseReducers, Name>): Slice<State, CaseReducers, Name>;
 
 // @public
-export interface CreateSliceOptions<State = any, CR extends SliceCaseReducers<State> = SliceCaseReducers<State>> {
+export interface CreateSliceOptions<State = any, CR extends SliceCaseReducers<State> = SliceCaseReducers<State>, Name extends string = string> {
     extraReducers?: CaseReducers<NoInfer<State>, any> | ((builder: ActionReducerMapBuilder<NoInfer<State>>) => void);
     initialState: State;
-    name: string;
+    name: Name;
     reducers: ValidateSliceCaseReducers<State, CR>;
 }
 
@@ -182,10 +182,10 @@ export interface SerializableStateInvariantMiddlewareOptions {
 }
 
 // @public
-export interface Slice<State = any, CaseReducers extends SliceCaseReducers<State> = SliceCaseReducers<State>> {
+export interface Slice<State = any, CaseReducers extends SliceCaseReducers<State> = SliceCaseReducers<State>, Name extends string = string> {
     actions: CaseReducerActions<CaseReducers>;
     caseReducers: SliceDefinedCaseReducers<CaseReducers>;
-    name: string;
+    name: Name;
     reducer: Reducer<State>;
 }
 
diff --git a/src/createSlice.ts b/src/createSlice.ts
index 58275d503..8b4e9c530 100644
--- a/src/createSlice.ts
+++ b/src/createSlice.ts
@@ -1,13 +1,13 @@
 import { Reducer } from 'redux'
 import {
+  ActionCreatorWithoutPayload,
   createAction,
   PayloadAction,
   PayloadActionCreator,
   PrepareAction,
-  ActionCreatorWithoutPayload,
   _ActionCreatorWithPreparedPayload
 } from './createAction'
-import { createReducer, CaseReducers, CaseReducer } from './createReducer'
+import { CaseReducer, CaseReducers, createReducer } from './createReducer'
 import {
   ActionReducerMapBuilder,
   executeReducerBuilderCallback
@@ -30,12 +30,13 @@ export type SliceActionCreator<P> = PayloadActionCreator<P>
  */
 export interface Slice<
   State = any,
-  CaseReducers extends SliceCaseReducers<State> = SliceCaseReducers<State>
+  CaseReducers extends SliceCaseReducers<State> = SliceCaseReducers<State>,
+  Name extends string = string
 > {
   /**
    * The slice name.
    */
-  name: string
+  name: Name
 
   /**
    * The slice's reducer.
@@ -62,12 +63,13 @@ export interface Slice<
  */
 export interface CreateSliceOptions<
   State = any,
-  CR extends SliceCaseReducers<State> = SliceCaseReducers<State>
+  CR extends SliceCaseReducers<State> = SliceCaseReducers<State>,
+  Name extends string = string
 > {
   /**
    * The slice's name. Used to namespace the generated action types.
    */
-  name: string
+  name: Name
 
   /**
    * The initial state to be returned by the slice reducer.
@@ -213,10 +215,11 @@ function getType(slice: string, actionKey: string): string {
  */
 export function createSlice<
   State,
-  CaseReducers extends SliceCaseReducers<State>
+  CaseReducers extends SliceCaseReducers<State>,
+  Name extends string = string
 >(
-  options: CreateSliceOptions<State, CaseReducers>
-): Slice<State, CaseReducers> {
+  options: CreateSliceOptions<State, CaseReducers, Name>
+): Slice<State, CaseReducers, Name> {
   const { name, initialState } = options
   if (!name) {
     throw new Error('`name` is a required option for createSlice')
diff --git a/type-tests/files/createSlice.typetest.ts b/type-tests/files/createSlice.typetest.ts
index 65f8008bc..ea459e1cd 100644
--- a/type-tests/files/createSlice.typetest.ts
+++ b/type-tests/files/createSlice.typetest.ts
@@ -1,22 +1,55 @@
-import { AnyAction, Reducer, Action } from 'redux'
+import { Action, AnyAction, Reducer } from 'redux'
+import { ValidateSliceCaseReducers } from 'src/createSlice'
 import {
-  createSlice,
-  PayloadAction,
-  createAction,
-  ActionReducerMapBuilder,
-  ActionCreatorWithOptionalPayload,
   ActionCreatorWithNonInferrablePayload,
+  ActionCreatorWithOptionalPayload,
   ActionCreatorWithoutPayload,
   ActionCreatorWithPayload,
   ActionCreatorWithPreparedPayload,
+  ActionReducerMapBuilder,
+  createAction,
+  createSlice,
+  PayloadAction,
   SliceCaseReducers
 } from '../../src'
-import { ValidateSliceCaseReducers } from 'src/createSlice'
 
 function expectType<T>(t: T) {
   return t
 }
 
+/*
+ * Test: Slice name is strongly typed.
+ */
+
+const counterSlice = createSlice({
+  name: 'counter',
+  initialState: 0,
+  reducers: {
+    increment: (state: number, action) => state + action.payload,
+    decrement: (state: number, action) => state - action.payload
+  }
+})
+
+const uiSlice = createSlice({
+  name: 'ui',
+  initialState: 0,
+  reducers: {
+    goToNext: (state: number, action) => state + action.payload,
+    goToPrevious: (state: number, action) => state - action.payload
+  }
+})
+
+const actionCreators = {
+  [counterSlice.name]: { ...counterSlice.actions },
+  [uiSlice.name]: { ...uiSlice.actions }
+}
+
+expectType<typeof counterSlice.actions>(actionCreators.counter)
+expectType<typeof uiSlice.actions>(actionCreators.ui)
+
+// typings:expect-error
+const value = actionCreators.anyKey
+
 /*
  * Test: createSlice() infers the returned slice's type.
  */