[Auth] Fix double-onAuthStateChanged call bug (#5686)

* Fix double-onAuthStateChanged call bug

* Add changeset

* PR feedback

Author: sam-gc

.changeset/thirty-rats-worry.md

@@ -0,0 +1,5 @@
+---
+"@firebase/auth": patch
+---
+
+Fix bug that caused onAuthStateChanged to be fired twice

packages/auth/src/core/auth/auth_impl.ts

@@ -139,6 +139,7 @@ export class AuthImpl implements AuthInternal, _FirebaseService {
       }
 
       await this.initializeCurrentUser(popupRedirectResolver);
+      this.lastNotifiedUid = this.currentUser?.uid || null;
 
       if (this._deleted) {
         return;

packages/auth/src/platform_browser/auth.test.ts

@@ -319,6 +319,25 @@ describe('core/auth/initializeAuth', () => {
       });
     });
 
+    it('initialization sets the callback UID correctly', async () => {
+      const stub = sinon.stub(
+        _getInstance<PersistenceInternal>(inMemoryPersistence)
+      );
+      stub._get.returns(Promise.resolve(testUser(oldAuth, 'uid').toJSON()));
+      let authStateChangeCalls = 0;
+
+      const auth = await initAndWait(inMemoryPersistence) as AuthInternal;
+      auth.onAuthStateChanged(() => {
+        authStateChangeCalls++;
+      });
+
+      await auth._updateCurrentUser(testUser(auth, 'uid'));
+      await new Promise(resolve => {
+        setTimeout(resolve, 200);
+      });
+      expect(authStateChangeCalls).to.eq(1);
+    });
+
     context('#tryRedirectSignIn', () => {
       it('returns null and clears the redirect user in case of error', async () => {
         const stub = sinon.stub(

packages/auth/test/integration/webdriver/persistence.test.ts

@@ -445,7 +445,7 @@ browserDescribe('WebDriver persistence test', (driver, browser) => {
       await driver.call(CoreFunction.SIGN_OUT);
       expect(await driver.getUserSnapshot()).to.be.null;
       await driver.selectMainWindow({ noWait: true });
-      await driver.pause(500);
+      await driver.pause(700);
       expect(await driver.getUserSnapshot()).to.be.null;
 
       const cred2: UserCredential = await driver.call(