Unexpected behaviour unit test in Streams (Dart) - unit-testing

Question

I'm using two libraries to make streams: the native and getX. I created two groups for tests: the native and getX with same contract from an abstract class (AnyPresenter). One of them is Stream<bool> get isLoadingStream which for the native is _state.isLoading and for getx is isLoading.
The Streams only change when run the method below:
Native:
Getx:
I'm using the same test for both, but it is not running correctly in the native test.
Expect result:
[true, false]
Native error:
This is the sample code:
import 'dart:async';
import 'package:get/get.dart';
import 'package:test/test.dart';
import 'package:mockito/mockito.dart';
class AnyState {
bool isLoading = false;
}
abstract class AnyPresenter {
Stream<bool> get isLoadingStream;
void doSomething();
}
class StreamAnyPresenter implements AnyPresenter {
final AnyLibrary anyLibrary;
var _controller = StreamController<AnyState>.broadcast();
var _anyState = AnyState();
StreamAnyPresenter(this.anyLibrary);
Stream<bool> get isLoadingStream =>
_controller.stream.map((anyState) => anyState.isLoading).distinct();
Future<void> doSomething() async {
_anyState.isLoading = true;
_controller.add(_anyState);
_anyState.isLoading = false;
_controller.add(_anyState);
}
}
class GetXPresenter implements AnyPresenter {
final AnyLibrary anyLibrary;
var isLoading = false.obs;
GetXPresenter(this.anyLibrary);
Stream<bool> get isLoadingStream => isLoading.stream.distinct();
Future<void> doSomething() async {
isLoading.value = true;
isLoading.value = false;
}
}
abstract class AnyLibrary {
Future<void> someMethod();
}
class AnyLibrarySpy extends Mock implements AnyLibrary {}
void main() {
AnyLibrarySpy anyLibrary;
setUp(() {
anyLibrary = AnyLibrarySpy();
});
group('Using native Stream', () {
StreamAnyPresenter sut;
setUp(() {
sut = StreamAnyPresenter(anyLibrary);
});
test('Should emit events on Success', () async {
expectLater(sut.isLoadingStream, emitsInOrder([true, false]));
await sut.doSomething();
});
});
group('Using getX', () {
GetXPresenter sut;
setUp(() {
sut = GetXPresenter(anyLibrary);
});
test('Should emit events on Success', () async {
expectLater(sut.isLoadingStream, emitsInOrder([true, false]));
await sut.doSomething();
});
});
}
Sorry for any mistakes. English is not my native language