Show last visited list on home page

src/modules/listHistory.js

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+export const getHistory = () => {
+	const savedHistory = localStorage.getItem('listHistory')
+	if (savedHistory === null) {
+		return []
+	}
+
+	return JSON.parse(savedHistory)
+}
+
+export function saveListToHistory(list) {
+	const history = getHistory()
+
+	// Remove the element if it already exists in history, preventing duplicates and essentially moving it to the beginning
+	for (const i in history) {
+		if (history[i].id === list.id) {
+			history.splice(i, 1)
+		}
+	}
+
+	history.unshift(list)
+
+	if (history.length > 5) {
+		history.pop()
+	}
+	localStorage.setItem('listHistory', JSON.stringify(history))
+}

src/modules/listHistory.test.js

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+import {getHistory, saveListToHistory} from './listHistory'
+
+test('return an empty history when none was saved', () => {
+	Storage.prototype.getItem = jest.fn(() => null)
+	const h = getHistory()
+	expect(h).toStrictEqual([])
+})
+
+test('return a saved history', () => {
+	const saved = [{id: 1}, {id: 2}]
+	Storage.prototype.getItem = jest.fn(() => JSON.stringify(saved))
+
+	const h = getHistory()
+	expect(h).toStrictEqual(saved)
+})
+
+test('store list in history', () => {
+	let saved = {}
+	Storage.prototype.getItem = jest.fn(() => null)
+	Storage.prototype.setItem = jest.fn((key, lists) => {
+		saved = lists
+	})
+
+	saveListToHistory({id: 1})
+	expect(saved).toBe('[{"id":1}]')
+})
+
+test('store only the last 5 lists in history', () => {
+	let saved = null
+	Storage.prototype.getItem = jest.fn(() => saved)
+	Storage.prototype.setItem = jest.fn((key, lists) => {
+		saved = lists
+	})
+
+	saveListToHistory({id: 1})
+	saveListToHistory({id: 2})
+	saveListToHistory({id: 3})
+	saveListToHistory({id: 4})
+	saveListToHistory({id: 5})
+	saveListToHistory({id: 6})
+	expect(saved).toBe('[{"id":6},{"id":5},{"id":4},{"id":3},{"id":2}]')
+})
+
+test('don\'t store the same list twice', () => {
+	let saved = null
+	Storage.prototype.getItem = jest.fn(() => saved)
+	Storage.prototype.setItem = jest.fn((key, lists) => {
+		saved = lists
+	})
+
+	saveListToHistory({id: 1})
+	saveListToHistory({id: 1})
+	expect(saved).toBe('[{"id":1}]')
+})
+
+test('move a list to the beginning when storing it multiple times', () => {
+	let saved = null
+	Storage.prototype.getItem = jest.fn(() => saved)
+	Storage.prototype.setItem = jest.fn((key, lists) => {
+		saved = lists
+	})
+
+	saveListToHistory({id: 1})
+	saveListToHistory({id: 2})
+	saveListToHistory({id: 1})
+	expect(saved).toBe('[{"id":1},{"id":2}]')
+})