Fix: captureTransaction should return emptyId when transaction is discarded (#713)

Author: marandaneto

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Unreleased
 
+* Fix: captureTransaction should return emptyId when transaction is discarded (#713)
+
 # 6.3.0-beta.3
 
 * Feat: Auto transactions duration trimming (#702)

dart/lib/src/sentry_client.dart

@@ -261,7 +261,7 @@ class SentryClient {
 
     final id = await captureEnvelope(
         SentryEnvelope.fromTransaction(preparedTransaction, _options.sdk));
-    return id!;
+    return id ?? SentryId.empty();
   }
 
   /// Reports the [envelope] to Sentry.io.

dart/test/sentry_client_test.dart

@@ -346,6 +346,14 @@ void main() {
 
       expect(capturedEvent['exception'], isNull);
     });
+
+    test('should return empty for when transaction is discarded', () async {
+      final client = fixture.getSut(eventProcessor: DropAllEventProcessor());
+      final tr = SentryTransaction(fixture.tracer);
+      final id = await client.captureTransaction(tr);
+
+      expect(id, SentryId.empty());
+    });
   });
 
   group('SentryClient : apply scope to the captured event', () {