Add a little more safety

src/locale/__tests__/helpers.test.ts

@@ -0,0 +1,12 @@
+import {test, expect} from '@jest/globals'
+
+import {sanitizeAppLanguageSetting} from '#/locale/helpers'
+import {AppLanguage} from '#/locale/languages'
+
+test('sanitizeAppLanguageSetting', () => {
+  expect(sanitizeAppLanguageSetting('en')).toBe(AppLanguage.en)
+  expect(sanitizeAppLanguageSetting('hi')).toBe(AppLanguage.hi)
+  expect(sanitizeAppLanguageSetting('foo')).toBe(AppLanguage.en)
+  expect(sanitizeAppLanguageSetting('en,fr')).toBe(AppLanguage.en)
+  expect(sanitizeAppLanguageSetting('fr,en')).toBe(AppLanguage.en)
+})

src/locale/helpers.ts

@@ -100,9 +100,7 @@ export function getTranslatorLink(text: string, lang: string): string {
  * and selects a new option, at which point we'll re-save their choice, which
  * should then be a valid option.
  */
-export function sanitizeAppLanguageSetting(
+export function sanitizeAppLanguageSetting(appLanguage: string): AppLanguage {
-  appLanguage: AppLanguage | string,
-): AppLanguage {
   const langs = appLanguage.split(',').filter(Boolean)
 
   for (const lang of langs) {

src/locale/languages.ts

@@ -10,13 +10,13 @@ export enum AppLanguage {
 }
 
 interface AppLanguageConfig {
-  code2: string
+  code2: AppLanguage
   name: string
 }
 
 export const APP_LANGUAGES: AppLanguageConfig[] = [
-  {code2: 'en', name: 'English'},
+  {code2: AppLanguage.en, name: 'English'},
-  {code2: 'hi', name: 'हिंदी'},
+  {code2: AppLanguage.hi, name: 'हिंदी'},
 ]
 
 export const LANGUAGES: Language[] = [

src/state/preferences/languages.tsx

@@ -1,5 +1,6 @@
 import React from 'react'
 import * as persisted from '#/state/persisted'
+import {AppLanguage} from '#/locale/languages'
 
 type SetStateCb = (
   s: persisted.Schema['languagePrefs'],
@@ -11,7 +12,7 @@ type ApiContext = {
   toggleContentLanguage: (code2: string) => void
   togglePostLanguage: (code2: string) => void
   savePostLanguageToHistory: () => void
-  setAppLanguage: (code2: string) => void
+  setAppLanguage: (code2: AppLanguage) => void
 }
 
 const stateContext = React.createContext<StateContext>(
@@ -23,7 +24,7 @@ const apiContext = React.createContext<ApiContext>({
   toggleContentLanguage: (_: string) => {},
   togglePostLanguage: (_: string) => {},
   savePostLanguageToHistory: () => {},
-  setAppLanguage: (_: string) => {},
+  setAppLanguage: (_: AppLanguage) => {},
 })
 
 export function Provider({children}: React.PropsWithChildren<{}>) {
@@ -106,7 +107,7 @@ export function Provider({children}: React.PropsWithChildren<{}>) {
             .slice(0, 6),
         }))
       },
-      setAppLanguage(code2: string) {
+      setAppLanguage(code2: AppLanguage) {
         setStateWrapped(s => ({...s, appLanguage: code2}))
       },
     }),

src/view/screens/LanguageSettings.tsx

@@ -61,7 +61,7 @@ export function LanguageSettingsScreen(_props: Props) {
     (value: Parameters<PickerSelectProps['onValueChange']>[0]) => {
       if (!value) return
       if (langPrefs.appLanguage !== value) {
-        setLangPrefs.setAppLanguage(value)
+        setLangPrefs.setAppLanguage(sanitizeAppLanguageSetting(value))
       }
     },
     [langPrefs, setLangPrefs],