Throw on invalid platform return type

[krocard]

Problem (PFL-69)

If the type returned from the platform side is not the expected one, invokeMethod returns null. We are handling it by returning default values.

Changes

As this should never happen, and if it was to, it would be a bug, throw an exception instead of hiding the issue.

Checklist

• 🗒 CHANGELOG entry if applicable

[krocard]

Wrapping in Future.error is unnecessary in an async function, it is equivalent to throw.
Additionally, the code was throwing a string when Dart recommends to only throw subclasses of Exception or Error.

[hawk23]

Nice improvement! 💪

During manual testing, I found a lot of those "Invalid type" exceptions in the console. A quick check revealed that now all calls of _invokeMethod<void>() fail with an exception now. I tested this on iOS but it should also fail on Android.

Also, flutter test integration_test fails now (we really should execute those in the CI soon 😅).

Some failing examples from player.dart

@override
Future<void> play() async => _invokeMethod<void>(Methods.play);

@override
Future<void> mute() async => _invokeMethod<void>(Methods.mute);

@override
Future<void> unmute() async => _invokeMethod<void>(Methods.unmute);

@override
Future<void> pause() async => _invokeMethod<void>(Methods.pause);

[hawk23]

Let's also print the method name for better debugging:

Suggested change

	throw Exception('Invalid type returned from the native platform side.');
	throw Exception('Invalid type returned for $methodName from the native platform side.');

[krocard]

Done

[krocard]

Done

[krocard]

During manual testing, I found a lot of those "Invalid type" exceptions in the console. A quick check revealed that now all calls of _invokeMethod() fail with an exception now. I tested this on iOS but it should also fail on Android.

Good catch. I was expecting the app to crash if any error was raised. I did not realized they would be logged. The issue was due to void being the only type for which T == T?. The problem should be fixed now.

Also, flutter test integration_test fails now (we really should execute those in the CI soon 😅).

I have not been able to run this the test locally. I guess some weird error:

$ flutter test integration_test
00:00 +0: loading /home/krocard/dev/bitmovin/bitmovin-player-flutter/example/integration_test/seeking_test.dart                                                                                                                        R../player_testing/lib/env/env.dart:3:6: Error: Error when reading '../player_testing/lib/env/env.g.dart': No such file or directory
part 'env.g.dart';
     ^
../player_testing/lib/env/env.dart:3:6: Error: Can't use '../player_testing/lib/env/env.g.dart' as a part, because it has no 'part of' declaration.
part 'env.g.dart';
     ^
../player_testing/lib/env/env.dart:14:50: Error: Undefined name '_Env'.
  static const String bitmovinPlayerLicenseKey = _Env.bitmovinPlayerLicenseKey;

But it does have a part of:

$ head -n3 ../player_testing/lib/env/env.dart
import 'package:envied/envied.dart';

part 'env.g.dart';

[hawk23]

I have not been able to run this the test locally. I guess some weird error:

Please have look at Integration Tests section in CONTRIBUTING.md. You need to create the .env file and run dart run build_runner build once to solve this.

[krocard]

I solved it by running dart run build_runner build in player_testing. Running it only in the root did not generate env.g.dart in player_testing (it did everywhere else but there).
I have no idea why. I even started a clean repo without observing differences.