[auth][android] resolve signOut return undefined #174 (#175)

* Update README.md

* Update index.d.ts

* Update index.android.ts

* Update index.ios.ts

* [Android] Fixe signOut return

* Cleanup

Author: kefahB

packages/firebase-auth/README.md

@@ -118,7 +118,18 @@ if (user && !user.emailVerified) {
 ### Signing Out
 
 ```ts
-firebase().auth().signOut();
+firebase().auth().signOut()
+.then(res => {
+  if(res) {
+    // user signed out
+    return
+  }
+  // else do staff
+});
+
+// OR
+
+let signedOut = await firebase().auth().signOut();
 ```
 
 ### Other sign-in methods

packages/firebase-auth/index.android.ts

@@ -1394,8 +1394,20 @@ export class Auth implements IAuth {
 		});
 	}
 
-	signOut() {
-		return this.native?.signOut?.();
+	async signOut(): Promise<boolean> {
+		return new Promise((resolve, reject) => {
+        this.native?.signOut();
+        let timeout = setTimeout(() => {
+            reject(false);
+        }, 3000);
+        this.addAuthStateChangeListener((user) => {
+            clearTimeout(timeout);
+            if(user) {
+                reject(false);
+            }
+            resolve(true);
+        });
+     })
 	}
 
 	get native() {

packages/firebase-auth/index.d.ts

@@ -357,7 +357,7 @@ export declare class Auth implements IAuth {
 
 	signInWithEmailLink(email: string, emailLink: string): Promise<UserCredential>;
 
-	signOut(): boolean;
+	signOut(): Promise<boolean>;
 
 	useUserAccessGroup(userAccessGroup: string): Promise<void>;
 

packages/firebase-auth/index.ios.ts

@@ -1237,8 +1237,8 @@ export class Auth implements IAuth {
 		});
 	}
 
-	signOut() {
-		return this.native?.signOut?.();
+	async signOut(): Promise<boolean> {
+		return await this.native?.signOut?.();
 	}
 
 	get native() {