add tests around redux favorite building hours

Author: drewvolz

source/redux/__tests__/buildings.test.ts

@@ -0,0 +1,32 @@
+import {reducer, State, toggleFavoriteBuilding} from '../parts/buildings'
+
+describe('toggle favorite building hours', () => {
+	it('should return the initial state', () => {
+		const {favorites} = reducer(undefined, {type: undefined})
+		expect(favorites).toEqual([])
+	})
+
+	it('should handle a favorite being added to an empty list', () => {
+		const previousState: State = {favorites: []}
+		const {favorites} = reducer(previousState, toggleFavoriteBuilding('a'))
+		expect(favorites).toEqual(['a'])
+	})
+
+	it('should handle a favorite being added to an existing list', () => {
+		const previousState: State = {favorites: ['a', 'b']}
+		const {favorites} = reducer(previousState, toggleFavoriteBuilding('c'))
+		expect(favorites).toEqual(['a', 'b', 'c'])
+	})
+
+	it('should handle a favorite being removed from an existing list', () => {
+		const previousState: State = {favorites: ['a']}
+		const {favorites} = reducer(previousState, toggleFavoriteBuilding('a'))
+		expect(favorites).toEqual([])
+	})
+
+	it('should handle a favorite being removed from an existing list of multiple favorites', () => {
+		const previousState: State = {favorites: ['a', 'b']}
+		const {favorites} = reducer(previousState, toggleFavoriteBuilding('a'))
+		expect(favorites).toEqual(['b'])
+	})
+})

source/redux/parts/buildings.ts

@@ -2,7 +2,7 @@ import {createSlice} from '@reduxjs/toolkit'
 import type {PayloadAction} from '@reduxjs/toolkit'
 import type {RootState} from '../store'
 
-type State = {
+export type State = {
 	favorites: Array<string>
 }