Bind root screen transaction to scope (#2756)

Author: denrase

CHANGELOG.md

@@ -10,6 +10,7 @@
 ### Fixes
 
 - Pass missing `captureFailedRequests` param to `FailedRequestInterceptor` ([#2744](https://github.com/getsentry/sentry-dart/pull/2744))
+- Bind root screen transaction to scope ([#2756](https://github.com/getsentry/sentry-dart/pull/2756))
 
 ### Dependencies
 

flutter/lib/src/integrations/native_app_start_handler.dart

@@ -37,22 +37,27 @@ class NativeAppStartHandler {
     // Create Transaction & Span
 
     const screenName = 'root /';
-    final transaction = _hub.startTransaction(
+    final rootScreenTransaction = _hub.startTransaction(
       screenName,
       SentrySpanOperations.uiLoad,
       startTimestamp: appStartInfo.start,
     );
 
+    // Bind to scope if null
+    await _hub.configureScope((scope) {
+      scope.span ??= rootScreenTransaction;
+    });
+
     await options.timeToDisplayTracker.track(
-      transaction,
+      rootScreenTransaction,
       startTimestamp: appStartInfo.start,
       endTimestamp: appStartInfo.end,
       origin: SentryTraceOrigins.autoUiTimeToDisplay,
     );
 
     SentryTracer sentryTracer;
-    if (transaction is SentryTracer) {
-      sentryTracer = transaction;
+    if (rootScreenTransaction is SentryTracer) {
+      sentryTracer = rootScreenTransaction;
     } else {
       return;
     }
@@ -62,8 +67,15 @@ class NativeAppStartHandler {
     sentryTracer.measurements[measurement.name] = appStartInfo.toMeasurement();
     await _attachAppStartSpans(appStartInfo, sentryTracer);
 
+    // Remove from scope
+    await _hub.configureScope((scope) {
+      if (scope.span == rootScreenTransaction) {
+        scope.span = null;
+      }
+    });
+
     // Finish Transaction
-    await transaction.finish(endTimestamp: appStartInfo.end);
+    await rootScreenTransaction.finish(endTimestamp: appStartInfo.end);
   }
 
   _AppStartInfo? _infoNativeAppStart(

flutter/lib/src/navigation/sentry_navigator_observer.dart

@@ -297,7 +297,7 @@ class SentryNavigatorObserver extends RouteObserver<PageRoute<dynamic>> {
     _transaction = null;
     try {
       _hub.configureScope((scope) {
-        if (scope.span == transaction) {
+        if (transaction != null && scope.span == transaction) {
           scope.span = null;
         }
       });

flutter/test/integrations/native_app_start_handler_test.dart

@@ -23,7 +23,12 @@ void main() {
       startTimestamp: anyNamed('startTimestamp'),
     )).thenReturn(fixture.tracer);
 
-    when(fixture.hub.configureScope(captureAny)).thenAnswer((_) {});
+    when(fixture.hub.configureScope(captureAny)).thenAnswer((invocation) {
+      final callback = invocation.positionalArguments[0] as ScopeCallback;
+      callback(fixture.scope);
+      return null;
+    });
+
     when(fixture.hub.captureTransaction(
       any,
       traceContext: anyNamed('traceContext'),
@@ -125,6 +130,25 @@ void main() {
         traceContext: captureAnyNamed('traceContext'),
       ));
     });
+
+    test('added transaction is bound to scope', () async {
+      await fixture.call(
+        appStartEnd: DateTime.fromMillisecondsSinceEpoch(10),
+      );
+      expect(fixture.scope.setSpans.length, 2);
+      expect(fixture.scope.setSpans[0], fixture.tracer);
+      expect(fixture.scope.setSpans[1], isNull);
+    });
+
+    test('added transaction is not bound to scope if already set', () async {
+      final alreadySet = MockSentryTracer();
+      fixture.scope.span = alreadySet;
+      await fixture.call(
+        appStartEnd: DateTime.fromMillisecondsSinceEpoch(10),
+      );
+      expect(fixture.scope.setSpans.length, 1);
+      expect(fixture.scope.setSpans[0], alreadySet);
+    });
   });
 
   group('App start spans', () {
@@ -306,6 +330,7 @@ class Fixture {
   final options = SentryFlutterOptions(dsn: fakeDsn);
   final nativeBinding = MockSentryNativeBinding();
   final hub = MockHub();
+  final scope = MockScope();
 
   late final tracer = SentryTracer(
     SentryTransactionContext(
@@ -343,3 +368,14 @@ class Fixture {
     return args[0] as SentryTransaction;
   }
 }
+
+class MockScope extends Mock implements Scope {
+  final setSpans = <ISentrySpan?>[];
+
+  @override
+  ISentrySpan? get span => setSpans.lastOrNull;
+  @override
+  set span(ISentrySpan? value) {
+    setSpans.add(value);
+  }
+}