[NoQA] LocaleCompare util tests

src/libs/LocaleCompare.ts

@@ -1,19 +1,26 @@
 import Onyx from 'react-native-onyx';
+import CONST from '@src/CONST';
 import ONYXKEYS from '@src/ONYXKEYS';
 
-const DEFAULT_LOCALE = 'en';
-
 const COLLATOR_OPTIONS: Intl.CollatorOptions = {usage: 'sort', sensitivity: 'base'};
 
-let collator = new Intl.Collator(DEFAULT_LOCALE, COLLATOR_OPTIONS);
+let collator = new Intl.Collator(CONST.LOCALES.DEFAULT, COLLATOR_OPTIONS);
 
 Onyx.connect({
     key: ONYXKEYS.NVP_PREFERRED_LOCALE,
     callback: (locale) => {
-        collator = new Intl.Collator(locale ?? DEFAULT_LOCALE, COLLATOR_OPTIONS);
+        collator = new Intl.Collator(locale ?? CONST.LOCALES.DEFAULT, COLLATOR_OPTIONS);
     },
 });
 
+/**
+ * This is a wrapper around the localeCompare function that uses the preferred locale from the user's settings.
+ *
+ * It re-uses Intl.Collator with static options for performance reasons. See https://github.com/facebook/hermes/issues/867 for more details.
+ * @param a
+ * @param b
+ * @returns -1 if a < b, 1 if a > b, 0 if a === b
+ */
 function localeCompare(a: string, b: string) {
     return collator.compare(a, b);
 }

tests/unit/LocaleCompareTest.js

@@ -0,0 +1,51 @@
+import Onyx from 'react-native-onyx';
+import localeCompare from '@libs/LocaleCompare';
+import CONST from '@src/CONST';
+import ONYXKEYS from '@src/ONYXKEYS';
+import waitForBatchedUpdates from '../utils/waitForBatchedUpdates';
+
+describe('localeCompare', () => {
+    beforeAll(() => {
+        Onyx.init({
+            keys: {NVP_PREFERRED_LOCALE: ONYXKEYS.NVP_PREFERRED_LOCALE},
+            initialKeyStates: {[ONYXKEYS.NVP_PREFERRED_LOCALE]: CONST.LOCALES.DEFAULT},
+        });
+        return waitForBatchedUpdates();
+    });
+
+    afterEach(() => Onyx.clear());
+
+    it('should return -1 for descending comparison', () => {
+        const result = localeCompare('Da Vinci', 'Tesla');
+
+        expect(result).toBe(-1);
+    });
+
+    it('should return -1 for ascending comparison', () => {
+        const result = localeCompare('Zidane', 'Messi');
+
+        expect(result).toBe(1);
+    });
+
+    it('should return 0 for equal strings', () => {
+        const result = localeCompare('Cat', 'Cat');
+
+        expect(result).toBe(0);
+    });
+
+    it('should discard sensitivity differences', () => {
+        const result = localeCompare('apple', 'Apple');
+
+        expect(result).toBe(0);
+    });
+
+    it('distinguishes spanish diacritic characters', async () => {
+        await Onyx.set(ONYXKEYS.NVP_PREFERRED_LOCALE, CONST.LOCALES.ES);
+
+        const input = ['zorro', 'árbol', 'jalapeño', 'jalapeno', 'nino', 'niño'];
+
+        input.sort(localeCompare);
+
+        expect(input).toEqual(['árbol', 'jalapeno', 'jalapeño', 'nino', 'niño', 'zorro']);
+    });
+});