feat: i18n user interface (#40306)

Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>

client/i18n/locales.test.js

@@ -0,0 +1,60 @@
+/* global expect */
+import { translationsSchema } from './translations-schema';
+import { motivationSchema } from './motivation-schema';
+import {
+  availableLangs,
+  i18nextCodes,
+  langDisplayNames,
+  langCodes
+} from './allLangs';
+
+const fs = require('fs');
+const { expectToMatchSchema, setup } = require('jest-json-schema-extended');
+
+setup();
+
+const filesThatShouldExist = [
+  {
+    name: 'translations.json',
+    schema: translationsSchema
+  },
+  {
+    name: 'motivation.json',
+    schema: motivationSchema
+  }
+];
+
+const path = `${process.cwd()}/i18n/locales`;
+
+describe('Locale tests:', () => {
+  availableLangs.client.forEach(lang => {
+    describe(`-- ${lang} --`, () => {
+      filesThatShouldExist.forEach(file => {
+        // check that each json file exists
+        test(`${file.name} file exists`, () => {
+          const exists = fs.existsSync(`${path}/${lang}/${file.name}`);
+          expect(exists).toBeTruthy();
+        });
+
+        // check that each of the json files match the schema
+        test(`${file.name} has correct schema`, async () => {
+          const jsonFile = fs.readFileSync(`${path}/${lang}/${file.name}`);
+          let json = await JSON.parse(jsonFile);
+          expectToMatchSchema(json, file.schema);
+        });
+      });
+
+      test(`has a two character entry in the i18nextCodes variable`, () => {
+        expect(i18nextCodes[lang].length).toBe(2);
+      });
+
+      test(`has an entry in the langDisplayNames variable`, () => {
+        expect(langDisplayNames[lang].length).toBeGreaterThan(0);
+      });
+
+      test(`has an entry in the langCodes variable`, () => {
+        expect(langCodes[lang].length).toBeGreaterThan(0);
+      });
+    });
+  });
+});