From d1f3afbabdcb44b7b7514cbbae4353823075a4c8 Mon Sep 17 00:00:00 2001
From: Brendan Daoud <brendan.daoud.theodo@ext.pmu.fr>
Date: Thu, 5 Sep 2019 15:11:35 +0200
Subject: [PATCH 1/2] Memoized utils methods for useMap

---
 src/__tests__/useMap.test.ts | 11 +++++++++++
 src/useMap.ts                | 20 +++++++++++---------
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/src/__tests__/useMap.test.ts b/src/__tests__/useMap.test.ts
index cc9d57a8..8108634a 100644
--- a/src/__tests__/useMap.test.ts
+++ b/src/__tests__/useMap.test.ts
@@ -106,3 +106,14 @@ it('should reset map to initial object provided', () => {
 
   expect(result.current[0]).toEqual({ foo: 'bar', a: 1 });
 });
+
+it('should memoized its utils methods', () => {
+  const { result } = setUp({ foo: 'bar', a: 1 });
+  const [, utils] = result.current;
+
+  act(() => {
+    utils.set('foo', 'baz');
+  });
+
+  expect(result.current[1]).toBe(utils);
+});
diff --git a/src/useMap.ts b/src/useMap.ts
index 2e1f896c..85a83b5a 100644
--- a/src/useMap.ts
+++ b/src/useMap.ts
@@ -1,4 +1,4 @@
-import { useState } from 'react';
+import { useState, useMemo } from 'react';
 
 export interface Actions<T extends object> {
   get: <K extends keyof T>(key: K) => T[K];
@@ -10,25 +10,27 @@ export interface Actions<T extends object> {
 const useMap = <T extends object = any>(initialMap: T = {} as T): [T, Actions<T>] => {
   const [map, set] = useState<T>(initialMap);
 
-  return [
-    map,
-    {
-      get: (key: keyof T) => map[key as string],
-      set: <K extends keyof T>(key: K, entry: T[K]) => {
+  const utils = useMemo<Actions<T>>(
+    () => ({
+      get: key => map[key],
+      set: (key, entry) => {
         set(prevMap => ({
           ...prevMap,
           [key]: entry,
         }));
       },
-      remove: (key: keyof T) => {
+      remove: key => {
         set(prevMap => {
           const { [key]: omit, ...rest } = prevMap;
           return rest as T;
         });
       },
       reset: () => set(initialMap),
-    },
-  ];
+    }),
+    [set]
+  );
+
+  return [map, utils];
 };
 
 export default useMap;

From 9e48050de4287d14cb342ef721eeb797b175772e Mon Sep 17 00:00:00 2001
From: Brendan Daoud <brendan.daoud.theodo@ext.pmu.fr>
Date: Thu, 5 Sep 2019 15:36:35 +0200
Subject: [PATCH 2/2] Test for 'set' callback also

---
 src/__tests__/useMap.test.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/__tests__/useMap.test.ts b/src/__tests__/useMap.test.ts
index 8108634a..fd7592f4 100644
--- a/src/__tests__/useMap.test.ts
+++ b/src/__tests__/useMap.test.ts
@@ -110,10 +110,12 @@ it('should reset map to initial object provided', () => {
 it('should memoized its utils methods', () => {
   const { result } = setUp({ foo: 'bar', a: 1 });
   const [, utils] = result.current;
+  const { set } = utils;
 
   act(() => {
-    utils.set('foo', 'baz');
+    set('foo', 'baz');
   });
 
   expect(result.current[1]).toBe(utils);
+  expect(result.current[1].set).toBe(set);
 });