Testing against it

The sink: RecordingTalkerObserver

OTelTalkerObserver — what the bridge forwards to — cannot be observed at all: it resolves OTel.loggerProvider() and throws without a live SDK, and OtelBridge swallows that, so "exported" and "dropped" look identical from outside. Pass a recording sink instead, and the floor, the breadcrumbs and the start-up summary all become assertable with no SDK and no collector:

final sink = RecordingTalkerObserver();
final zone = OtelZone(config, sink: sink);

sink.records is everything forwarded to it, oldest first. The bridge on its own works the same way:

final sink = RecordingTalkerObserver();
final bridge = OtelBridge(
  floor: const ExportFloor.of(LogLevel.warning),
  history: () => const <TalkerData>[],
  sink: sink,
)..ready = true;

bridge.onLog(TalkerData('a route change', logLevel: LogLevel.info));
sink.records; // empty — info is below the floor

ready is what start() sets on success; nothing is forwarded while it is false, so a bridge under test sets it by hand.

The start-up line

startupSummary is public, so the line a build will log can be asserted without starting anything:

const config = OtelZoneConfig(
  serviceName: 'my-app',
  endpoint: 'https://otel.example.com',
  deploymentEnvironmentName: 'production',
);
final zone = OtelZone(config, sink: RecordingTalkerObserver());
zone.startupSummary('1.2.3', '48');
// 'OpenTelemetry: exporting to https://otel.example.com as my-app '
// '1.2.3 build 48 (production), records at warning and above'

The crash screen

The screen setCrashScreen gives the platform goes to a crashScreenSink, and RecordingCrashScreenSink is its fake. Pass one to see what the platform would have been told:

final crashScreen = RecordingCrashScreenSink();
final zone = OtelZone(config, sink: sink, crashScreenSink: crashScreen);
zone.setCrashScreen('/orders/:id');
crashScreen.screens; // ['/orders/:id'], once the message has been sent

Under flutter test the default sink is none, so without one nothing is sent.

Native crashes: NativeCrashSource

OtelZone's nativeCrashSource: parameter is the seam the crash drain is tested through. Implement pending() and acknowledge(ids) to stand in for the platform without a method channel or a device:

class FakeCrashSource implements NativeCrashSource {
  final List<String> acknowledged = <String>[];

  @override
  Future<List<NativeCrashReport>> pending() async => <NativeCrashReport>[
    NativeCrashReport(id: 'a', kind: 'native', timestampMicros: 1700000000000000),
  ];

  @override
  Future<void> acknowledge(List<String> ids) async => acknowledged.addAll(ids);
}

Injection points, all together

Parameter	Default	Replace it with
talker	a Talker with the bridge as its observer	your own (give it bridge yourself)
sink	OTelTalkerObserver	RecordingTalkerObserver
nativeCrashSource	PigeonNativeCrashSource (the plugin's channel)	any NativeCrashSource
crashScreenSink	PigeonCrashScreenSink, none under flutter test	RecordingCrashScreenSink

A caller that supplies its own talker is responsible for having given it the zone's bridge as an observer.

Testing this package

flutter test in the repository is the whole contract — the floor, the breadcrumbs, the redaction and the start-up summary — and needs no device. See Building and testing for the web, Kotlin and Swift suites.