[firebase_auth] Fix NoSuchMethodError exception in reauthenticateWithCredential

[fabriziocacicia]

Fix NoSuchMethodError exception when calling FirebaseUser.reauthenticateWithCredential

Description

The stacktrace of the issue was this:

#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
#1      new AuthResult._ (package:firebase_auth/src/auth_result.dart:12:36)
#2      FirebaseUser.reauthenticateWithCredential (package:firebase_auth/src/firebase_user.dart:213:23)
<asynchronous suspension>
#3      ...............

This is the relevant part in auth_result.dart:

class AuthResult {
  AuthResult._(this._data, FirebaseApp app)
      : user = FirebaseUser._(_data['user'].cast<String, dynamic>(), app);

  final Map<String, dynamic> _data;

So, the data parameter passed to the FirebaseUser constructor was null.

From the reauthenticateWithCredential method:

Future<AuthResult> reauthenticateWithCredential(
      AuthCredential credential) async {
    assert(credential != null);
    final Map<String, dynamic> data =
        await FirebaseAuth.channel.invokeMapMethod<String, dynamic>(
      'reauthenticateWithCredential',
      <String, dynamic>{
        'app': _app.name,
        'provider': credential._provider,
        'data': credential._data,
      },
    );
    return AuthResult._(data, _app);
  }

the data parameter passed to AuhtResult came from the reauthenticateWithCredential invoked channel method.

By looking inside the handleReauthenticateWithCredential method in the FirebaseAuthPlugin.java I notice the line:

currentUser
        .reauthenticate(credential)
        .addOnCompleteListener(new TaskVoidCompleteListener(result));

The reauthenticate has a return type of Task<void>, for this reason, the data in the reauthenticateWithCredential was filled with null.
The FirebaseUser's reauthenticateAndRetrieveData method has Task<AuthResult> as return type. Also the SignInCompleteListener returns a map containing the Firebase user data inside the "user" key (exactly what the AuthResult needs in its constructor).
By applying these two modifications the code works properly.

Related Issues

Fixes #76
Fixes #1085

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[fabriziocacicia]

I can't figure out why the build fails

[hungnt-kayac]

@fabryx92 i think you also have to fix ios plugin.
in that case, i've took a look at
https://github.com/FirebaseExtended/flutterfire/blob/master/packages/firebase_auth/ios/Classes/FirebaseAuthPlugin.m#L238-L244
and found that it didn't set return object.
in my opinion, i think it should be

else if ([@"reauthenticateWithCredential" isEqualToString:call.method]) {
    [[self getAuth:call.arguments].currentUser
        reauthenticateAndRetrieveDataWithCredential:[self getCredential:call.arguments]
                                         completion:^(FIRAuthDataResult *r, NSError *error) {
                                           [self sendResult:result forAuthDataResult:r error:error];
                                         }];
  }

[fabriziocacicia]

@hungnt-kayac thank you! You are right, I focused only on the Android part. I'm not very familiar with ios development, maybe because of this, I forgot it. Your reply was really helpful!

[fabriziocacicia]

Why now the build fails? Editing the changelog only? I did again all the steps written in the Contribution guide to be sure that all is fine, and it is.