fix(localize): don't fire localeChanged event if set to the same locale

Author: Mikhail Bashkirov

packages/localize/src/LocalizeManager.js

@@ -181,6 +181,9 @@ export class LocalizeManager extends LionSingleton {
   }
 
   _onLocaleChanged(newLocale, oldLocale) {
+    if (newLocale === oldLocale) {
+      return;
+    }
     this.dispatchEvent(new CustomEvent('localeChanged', { detail: { newLocale, oldLocale } }));
     if (this._autoLoadOnLocaleChange) {
       this._loadAllMissing(newLocale, oldLocale);

packages/localize/test/LocalizeManager.test.js

@@ -1,4 +1,5 @@
 import { expect, oneEvent } from '@open-wc/testing';
+import sinon from 'sinon';
 import { fetchMock } from '@bundled-es-modules/fetch-mock';
 import { setupFakeImport, resetFakeImport, fakeImport } from './test-utils.js';
 
@@ -48,6 +49,15 @@ describe('LocalizeManager', () => {
     expect(event.detail.oldLocale).to.equal('en-GB');
   });
 
+  it('does not fire "localeChanged" event if it was set to the same locale', () => {
+    const manager = new LocalizeManager();
+    const eventSpy = sinon.spy();
+    manager.addEventListener('localeChanged', eventSpy);
+    manager.locale = 'en-US';
+    manager.locale = 'en-US';
+    expect(eventSpy.callCount).to.equal(1);
+  });
+
   describe('addData()', () => {
     it('allows to provide inline data', () => {
       const manager = new LocalizeManager();