[firebase_auth] Add missing method getIdTokenResult()

[lukaspili]

Description

Firebase auth is missing the method getIdTokenResult() which is available on native SDKs. It allows to retrieve the current token + other useful info like the token custom claims.

The PR includes the changes:

• Add new public API on dart side: Future<IdTokenResult> getIdTokenResult(bool refresh)
• Add new object on dart side: IdTokenResult
• Add new method call handler on iOS, which calls the native firebase getIdTokenResult(BOOL refresh)
• Update the method call handler getIdToken on Android, in order to handle both getIdToken() and getIdTokenResult(). The reason is the firebase Android SDK only provides one method getIdToken, which returns the id token result. The method now returns only the token or the whole token result, depending on the dart call.

What is missing: tests, changelog, version bump.
Will add these later.

Related Issues

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[collinjackson]

Thanks for the PR! This is looking good, just a few requests around testing and make sure to reformat so that the bots are happy.

Could you please add unit tests for the added MethodChannel API surface area to test/firebase_auth_test.dart

Could you please also add integration tests to example/test_driver/firebase_auth.dart. Something like this:

    test('idTokenResult', () async {
      final FirebaseUser user = await auth.signInAnonymously();
      String token = await user.getIdToken();
      expect(token, isNotNull);
      IdTokenResult result = await user.getIdTokenResult();
      expect(result.token, token);
      // more assertions here
    });

[collinjackson]

Suggested change

	// Contrary to iOS, android has a single method to handle getIdToken() and getIdTokenResult()
	// Contrary to iOS, Android has a single method to handle `getIdToken()` and `getIdTokenResult()`

[collinjackson]

After looking at this more carefully, I think that getIdToken() should probably return a result object that can be used to get the token. This is a breaking API change, so I'll get some internal feedback about naming.

[lukaspili]

I understand, in my opinion there should be only but 1 method. Javascript and iOS Firebase SDKs provide 2 methods, while Android SDK provides only 1.

What about deprecating getIdToken() (which currently returns the token string) and adding the new method getIdTokenResult() (which will return the result object)?

[collinjackson]

Haven't forgotten about this one, I should have a naming decision soon and then we can move forward. Thanks for your patience.

[lukaspili]

No problem. I'll wait on your decision before implementing the tests.

[collinjackson]

The feedback that I got from naming committee was to change the signature of getIdToken to Future<IdTokenResult> getIdToken({bool refresh = false});. And at the same time make a breaking change to sign-in methods so that they return an AuthResult instead of a FirebaseUser. We are choosing to diverge from the React Native / web SDK's UserCredential naming and two getIdToken* methods that are there for historical reasons.

[lukaspili]

Implemented changes for renaming, updated the tests and the changelog.
PTAL.

[collinjackson]

I think we should call it authTime rather than authDate to be a bit more idiomatic: this matches the naming conventions of the web SDK, matches React Native Firebase, and reflects that the granularity of the data includes time info.

This lines up with what's happening in #1919 where I want to change Timestamp to Time in the Dart API.

[lukaspili]

Makes sense. Let me know if there is anything else I can do.

[lookfirst]

@collinjackson lol, I was just looking for this and couldn't find it in 0.11! I guess I'll have to try your new version asap. =)