redux-promise-middleware: fix Dispatch return type

When the payload is a Promise, the Promise Middleware will change what
`dispatch()` returns. Reflect this with typing.
According to documentation [1], it is a Promise of an object with the
promised `value` and the FULFILLED action `type`.

[1] https://github.com/pburtchaell/redux-promise-middleware/blob/master/docs/guides/chaining-actions.md

types/redux-promise-middleware/index.d.ts

@@ -2,7 +2,23 @@
 // Project: https://github.com/pburtchaell/redux-promise-middleware
 // Definitions by: ianks <https://github.com/ianks>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
+// TypeScript Version: 2.8
 
 import { Middleware } from 'redux';
 
 export default function promiseMiddleware(config?: { promiseTypeSuffixes?: string[], promiseTypeDelimiter?: string }): Middleware;
+
+declare module "redux" {
+  export interface PromiseAction<R> extends Action {
+    payload: Promise<R>;
+  }
+
+  type PayloadType<PA> = PA extends PromiseAction<infer R> ? R : never;
+
+  export interface Dispatch<S> {
+    <R, PA extends PromiseAction<R>>(action: PA): Promise<{
+      value: PayloadType<PA>;
+      type: string;
+    }>;
+  }
+}

types/redux-promise-middleware/redux-promise-middleware-tests.ts

@@ -2,7 +2,6 @@ import { createStore, applyMiddleware, Store, Dispatch } from "redux";
 import promiseMiddleware from "redux-promise-middleware";
 
 declare var rootReducer: (state: any, action: any) => any;
-declare var Promise: any;
 declare var doSomethingAsyncAndReturnPromise: any;
 declare var someActionCreator: any;
 
@@ -38,6 +37,8 @@ const actionCreator2 = () => ({
     promise: Promise.resolve((action: string, dispatch: Dispatch<any>, getState: Function) => {
       dispatch({ type: "SECEOND_ACTION_TYPE", payload: "..." });
       dispatch(someActionCreator());
+      dispatch({ type: "CHAINED_ACTION", payload: Promise.resolve("...") })
+        .then(({ type, value }) => {})
     })
    }
 });