fix(auth, emulator): guard against double useEmulator calls

in case javascript hot reloads, track useEmulator calls natively and
drop calls after the first one

Author: mikehardy

packages/auth/android/src/main/java/io/invertase/firebase/auth/ReactNativeFirebaseAuthModule.java

@@ -75,6 +75,7 @@ class ReactNativeFirebaseAuthModule extends ReactNativeFirebaseModule {
   private static final String TAG = "Auth";
   private static HashMap<String, FirebaseAuth.AuthStateListener> mAuthListeners = new HashMap<>();
   private static HashMap<String, FirebaseAuth.IdTokenListener> mIdTokenListeners = new HashMap<>();
+  private static HashMap<String, String> emulatorConfigs = new HashMap<>();
   private String mVerificationId;
   private String mLastPhoneNumber;
   private PhoneAuthProvider.ForceResendingToken mForceResendingToken;
@@ -1561,10 +1562,13 @@ public void verifyPasswordResetCode(String appName, String code, final Promise p
 
   @ReactMethod
   public void useEmulator(String appName, String host, int port) {
-    Log.d(TAG, "useEmulator");
-    FirebaseApp firebaseApp = FirebaseApp.getInstance(appName);
-    FirebaseAuth firebaseAuth = FirebaseAuth.getInstance(firebaseApp);
-    firebaseAuth.useEmulator(host, port);
+
+    if (emulatorConfigs.get(appName) == null) {
+      emulatorConfigs.put(appName, "true");
+      FirebaseApp firebaseApp = FirebaseApp.getInstance(appName);
+      FirebaseAuth firebaseAuth = FirebaseAuth.getInstance(firebaseApp);
+      firebaseAuth.useEmulator(host, port);
+    }
   }
 
   /* ------------------

packages/auth/ios/RNFBAuth/RNFBAuthModule.m

@@ -50,6 +50,7 @@
 
 static __strong NSMutableDictionary *authStateHandlers;
 static __strong NSMutableDictionary *idTokenHandlers;
+static __strong NSMutableDictionary *emulatorConfigs;
 // Used for caching credentials between method calls.
 static __strong NSMutableDictionary<NSString *, FIRAuthCredential *> *credentials;
 
@@ -69,6 +70,7 @@ - (id)init {
   dispatch_once(&onceToken, ^{
     authStateHandlers = [[NSMutableDictionary alloc] init];
     idTokenHandlers = [[NSMutableDictionary alloc] init];
+    emulatorConfigs = [[NSMutableDictionary alloc] init];
     credentials = [[NSMutableDictionary alloc] init];
   });
   return self;
@@ -940,7 +942,10 @@ - (void)invalidate {
                   : (FIRApp *)firebaseApp
                   : (nonnull NSString *)host
                   : (NSInteger)port) {
-  [[FIRAuth authWithApp:firebaseApp] useEmulatorWithHost:host port:port];
+  if (!emulatorConfigs[firebaseApp.name]) {
+    [[FIRAuth authWithApp:firebaseApp] useEmulatorWithHost:host port:port];
+    emulatorConfigs[firebaseApp.name] = @YES;
+  }
 }
 
 - (FIRAuthCredential *)getCredentialForProvider:(NSString *)provider