Adds docs and fix test.

Author: EskiMojo14

docs/api/actionCreatorMiddleware.mdx

@@ -0,0 +1,67 @@
+---
+id: actionCreatorMiddleware
+title: Action Creator Middleware
+sidebar_label: Action Creator Middleware
+hide_title: true
+---
+
+ 
+
+# Action Creator Middleware
+
+A custom middleware that detects if an action creator has been mistakenly dispatched, instead of being called before dispatching.
+
+A common mistake is to call `dispatch(actionCreator)` instead of `dispatch(actionCreator())`.
+This tends to "work" as the action creator has the static `type` property, but can lead to unexpected behaviour.
+
+## Options
+
+```ts no-transpile
+export interface ActionCreatorInvariantMiddlewareOptions {
+  /**
+   * The function to identify whether a value is an action creator.
+   * The default checks for a function with a static type property and match method.
+   */
+  isActionCreator?: (action: unknown) => action is Function & { type?: unknown }
+}
+```
+
+## Exports
+
+### `createActionCreatorInvariantMiddleware`
+
+Creates an instance of the action creator check middleware, with the given options.
+
+You will most likely not need to call this yourself, as `getDefaultMiddleware` already does so.
+Example:
+
+```ts
+// file: reducer.ts noEmit
+
+export default function (state = {}, action: any) {
+  return state
+}
+
+// file: store.ts
+
+import {
+  configureStore,
+  createActionCreatorInvariantMiddleware,
+} from '@reduxjs/toolkit'
+import reducer from './reducer'
+
+// Augment middleware to consider all functions with a static type property to be action creators
+const isActionCreator = (
+  action: unknown
+): action is Function & { type: unknown } =>
+  typeof action === 'function' && 'type' in action
+
+const actionCreatorMiddleware = createActionCreatorInvariantMiddleware({
+  isActionCreator,
+})
+
+const store = configureStore({
+  reducer,
+  middleware: [actionCreatorMiddleware],
+})
+```

docs/api/getDefaultMiddleware.mdx

@@ -70,7 +70,7 @@ It is preferable to use the chainable `.concat(...)` and `.prepend(...)` methods
 
 One of the goals of Redux Toolkit is to provide opinionated defaults and prevent common mistakes. As part of that,
 `getDefaultMiddleware` includes some middleware that are added **in development builds of your app only** to
-provide runtime checks for two common issues:
+provide runtime checks for three common issues:
 
 - [Immutability check middleware](./immutabilityMiddleware.mdx): deeply compares
   state values for mutations. It can detect mutations in reducers during a dispatch, and also mutations that occur between
@@ -82,13 +82,21 @@ provide runtime checks for two common issues:
   such as functions, Promises, Symbols, and other non-plain-JS-data values. When a non-serializable value is detected, a
   console error will be printed with the key path for where the non-serializable value was detected.
 
+- [Action creator check middleware](./actionCreatorMiddleware.mdx): another custom middleware created specifically for use in Redux Toolkit.
+  Identifies when an action creator was mistakenly dispatched without being called, and warns to console with the action type.
+
 In addition to these development tool middleware, it also adds [`redux-thunk`](https://github.com/reduxjs/redux-thunk)
 by default, since thunks are the basic recommended side effects middleware for Redux.
 
 Currently, the return value is:
 
 ```js
-const middleware = [thunk, immutableStateInvariant, serializableStateInvariant]
+const middleware = [
+  immutableStateInvariant,
+  thunk,
+  serializableStateInvariant,
+  actionCreatorInvariant,
+]
 ```
 
 ### Production
@@ -153,10 +161,15 @@ interface SerializableStateInvariantMiddlewareOptions {
   // See "Serializability Middleware" page for definition
 }
 
+interface ActionCreatorInvariantMiddlewareOptions {
+  // See "Action Creator Middleware" page for definition
+}
+
 interface GetDefaultMiddlewareOptions {
   thunk?: boolean | ThunkOptions
   immutableCheck?: boolean | ImmutableStateInvariantMiddlewareOptions
   serializableCheck?: boolean | SerializableStateInvariantMiddlewareOptions
+  actionCreatorCheck?: boolean | ActionCreatorInvariantMiddlewareOptions
 }
 
 function getDefaultMiddleware<S = any>(

packages/toolkit/src/tests/configureStore.test.ts

@@ -75,9 +75,10 @@ describe('configureStore', () => {
         Object
       )
       expect(redux.applyMiddleware).toHaveBeenCalledWith(
-        expect.any(Function), // thunk
         expect.any(Function), // immutableCheck
-        expect.any(Function) // serializableCheck
+        expect.any(Function), // thunk
+        expect.any(Function), // serializableCheck
+        expect.any(Function) // actionCreatorCheck
       )
       expect(devtools.composeWithDevTools).toHaveBeenCalled() // @remap-prod-remove-line-line
       expect(redux.createStore).toHaveBeenCalledWith(

website/sidebars.json

@@ -41,6 +41,7 @@
             "api/getDefaultMiddleware",
             "api/immutabilityMiddleware",
             "api/serializabilityMiddleware",
+            "api/actionCreatorMiddleware",
             "api/createListenerMiddleware",
             "api/autoBatchEnhancer"
           ]