From e4f661ba43610a64ecaf0877ad38cef44313bb7f Mon Sep 17 00:00:00 2001
From: Oliver Joseph Ash <oliverjash@gmail.com>
Date: Fri, 19 Apr 2019 16:44:41 +0100
Subject: [PATCH] react-redux: correct `mapDispatchToProps` param type (#34498)

* react-redux: correct `mapDispatchToProps` param type

Fixes https://github.com/DefinitelyTyped/DefinitelyTyped/issues/34493

* Complete explanation

* Move test
---
 types/react-redux/index.d.ts            |  8 +++---
 types/react-redux/react-redux-tests.tsx | 33 ++++++++++++++++++++++---
 2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/types/react-redux/index.d.ts b/types/react-redux/index.d.ts
index 1b2ababe14..5d9f01249a 100644
--- a/types/react-redux/index.d.ts
+++ b/types/react-redux/index.d.ts
@@ -171,7 +171,7 @@ export interface Connect {
 
     <no_state = {}, TDispatchProps = {}, TOwnProps = {}>(
         mapStateToProps: null | undefined,
-        mapDispatchToProps: TDispatchProps,
+        mapDispatchToProps: MapDispatchToPropsParam<TDispatchProps, TOwnProps>,
     ): InferableComponentEnhancerWithProps<
         ResolveThunks<TDispatchProps>,
         TOwnProps
@@ -184,7 +184,7 @@ export interface Connect {
 
     <TStateProps = {}, TDispatchProps = {}, TOwnProps = {}, State = {}>(
         mapStateToProps: MapStateToPropsParam<TStateProps, TOwnProps, State>,
-        mapDispatchToProps: TDispatchProps,
+        mapDispatchToProps: MapDispatchToPropsParam<TDispatchProps, TOwnProps>,
     ): InferableComponentEnhancerWithProps<
         TStateProps & ResolveThunks<TDispatchProps>,
         TOwnProps
@@ -231,7 +231,7 @@ export interface Connect {
 
     <TStateProps = {}, TDispatchProps = {}, TOwnProps = {}>(
         mapStateToProps: null | undefined,
-        mapDispatchToProps: TDispatchProps,
+        mapDispatchToProps: MapDispatchToPropsParam<TDispatchProps, TOwnProps>,
         mergeProps: null | undefined,
         options: Options<{}, TStateProps, TOwnProps>
     ): InferableComponentEnhancerWithProps<
@@ -248,7 +248,7 @@ export interface Connect {
 
     <TStateProps = {}, TDispatchProps = {}, TOwnProps = {}, State = {}>(
         mapStateToProps: MapStateToPropsParam<TStateProps, TOwnProps, State>,
-        mapDispatchToProps: TDispatchProps,
+        mapDispatchToProps: MapDispatchToPropsParam<TDispatchProps, TOwnProps>,
         mergeProps: null | undefined,
         options: Options<State, TStateProps, TOwnProps>
     ): InferableComponentEnhancerWithProps<
diff --git a/types/react-redux/react-redux-tests.tsx b/types/react-redux/react-redux-tests.tsx
index 085874a523..95fcbc9dee 100644
--- a/types/react-redux/react-redux-tests.tsx
+++ b/types/react-redux/react-redux-tests.tsx
@@ -1,7 +1,7 @@
 import * as React from 'react';
 import * as ReactDOM from 'react-dom';
 import { Store, Dispatch, AnyAction, ActionCreator, createStore, bindActionCreators, ActionCreatorsMapObject, Reducer } from 'redux';
-import { Connect, connect, Provider, DispatchProp, MapStateToProps, Options, ReactReduxContext, ReactReduxContextValue, Selector } from 'react-redux';
+import { Connect, connect, Provider, DispatchProp, MapStateToProps, Options, ReactReduxContext, ReactReduxContextValue, Selector, MapDispatchToProps } from 'react-redux';
 import objectAssign = require('object-assign');
 
 //
@@ -82,9 +82,34 @@ function MapDispatch() {
 
     class TestComponent extends React.Component<OwnProps & DispatchProps> { }
 
-    const mapDispatchToProps = () => ({
-        onClick: () => { }
-    });
+    const mapDispatchToProps = ({ onClick: () => {} });
+
+    const TestNull = connect(
+        null,
+        mapDispatchToProps,
+    )(TestComponent);
+
+    const verifyNull = <TestNull foo='bar' />;
+
+    const TestUndefined = connect(
+        undefined,
+        mapDispatchToProps,
+    )(TestComponent);
+
+    const verifyUndefined = <TestUndefined foo='bar' />;
+}
+
+function MapDispatchUnion() {
+    interface OwnProps { foo: string; }
+    interface DispatchProps { onClick: () => void; }
+
+    class TestComponent extends React.Component<OwnProps & DispatchProps> { }
+
+    // We deliberately cast the right-hand side to `any` because otherwise
+    // TypeScript would maintain the literal value, when we deliberately want to
+    // test the union type here (as per the annotation). See
+    // https://github.com/Microsoft/TypeScript/issues/30310#issuecomment-472218182.
+    const mapDispatchToProps: MapDispatchToProps<DispatchProps, OwnProps> = {} as any;
 
     const TestNull = connect(
         null,