From df36f4efa47a32954b9d14c2c3b5c3e9c0cc795d Mon Sep 17 00:00:00 2001
From: Gregory Shilin <gshilin@gmail.com>
Date: Wed, 31 Mar 2021 05:08:06 +0300
Subject: [PATCH] Verify that selector and equalityF of useSelector are
 functions (#1706)

See https://github.com/reduxjs/react-redux/issues/1704
---
 src/hooks/useSelector.js       | 14 ++++++++++++--
 test/hooks/useSelector.spec.js |  8 ++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/hooks/useSelector.js b/src/hooks/useSelector.js
index 87b61f244..85e85d13e 100644
--- a/src/hooks/useSelector.js
+++ b/src/hooks/useSelector.js
@@ -107,8 +107,18 @@ export function createSelectorHook(context = ReactReduxContext) {
       ? useDefaultReduxContext
       : () => useContext(context)
   return function useSelector(selector, equalityFn = refEquality) {
-    if (process.env.NODE_ENV !== 'production' && !selector) {
-      throw new Error(`You must pass a selector to useSelector`)
+    if (process.env.NODE_ENV !== 'production') {
+      if (!selector) {
+        throw new Error(`You must pass a selector to useSelector`)
+      }
+      if (typeof selector !== 'function') {
+        throw new Error(`You must pass a function as a selector to useSelector`)
+      }
+      if (typeof equalityFn !== 'function') {
+        throw new Error(
+          `You must pass a function as an equality function to useSelector`
+        )
+      }
     }
     const { store, subscription: contextSub } = useReduxContext()
 
diff --git a/test/hooks/useSelector.spec.js b/test/hooks/useSelector.spec.js
index 0af0176c7..17d7a80aa 100644
--- a/test/hooks/useSelector.spec.js
+++ b/test/hooks/useSelector.spec.js
@@ -451,6 +451,14 @@ describe('React', () => {
         it('throws if no selector is passed', () => {
           expect(() => useSelector()).toThrow()
         })
+
+        it('throws if selector is not a function', () => {
+          expect(() => useSelector(1)).toThrow()
+        })
+
+        it('throws if equality function is not a function', () => {
+          expect(() => useSelector((s) => s.count, 1)).toThrow()
+        })
       })
     })