add SentryEnvelopeHeader to SentryEnvelopeHeader

Author: denrase

dart/lib/src/sentry_envelope_header.dart

@@ -1,6 +1,7 @@
 import 'protocol/sentry_id.dart';
 import 'protocol/sdk_version.dart';
 import 'sentry_trace_context_header.dart';
+import 'utils.dart';
 
 /// Header containing `SentryId` and `SdkVersion`.
 class SentryEnvelopeHeader {
@@ -9,12 +10,14 @@ class SentryEnvelopeHeader {
     this.sdkVersion, {
     this.dsn,
     this.traceContext,
+    this.sentAt,
   });
   SentryEnvelopeHeader.newEventId()
       : eventId = SentryId.newId(),
         sdkVersion = null,
         dsn = null,
-        traceContext = null;
+        traceContext = null,
+        sentAt = null;
 
   /// The identifier of encoded `SentryEvent`.
   final SentryId? eventId;
@@ -27,6 +30,8 @@ class SentryEnvelopeHeader {
   /// The `DSN` of the Sentry project.
   final String? dsn;
 
+  DateTime? sentAt;
+
   /// Header encoded as JSON
   Map<String, dynamic> toJson() {
     final json = <String, dynamic>{};
@@ -49,6 +54,11 @@ class SentryEnvelopeHeader {
     if (dsn != null) {
       json['dsn'] = dsn;
     }
+
+    if (sentAt != null) {
+      json['sent_at'] = formatDateAsIso8601WithMillisPrecision(sentAt!);
+    }
+
     return json;
   }
 }

dart/test/sentry_envelope_header_test.dart

@@ -1,5 +1,6 @@
 import 'package:sentry/sentry.dart';
 import 'package:sentry/src/sentry_envelope_header.dart';
+import 'package:sentry/src/utils.dart';
 import 'package:test/test.dart';
 
 import 'mocks.dart';
@@ -22,18 +23,21 @@ void main() {
         'trace_id': '${SentryId.newId()}',
         'public_key': '123',
       });
+      final timestamp = DateTime.utc(2019);
       final sut = SentryEnvelopeHeader(
         eventId,
         sdkVersion,
         dsn: fakeDsn,
         traceContext: context,
+        sentAt: timestamp,
       );
       final expextedSkd = sdkVersion.toJson();
       final expected = <String, dynamic>{
         'event_id': eventId.toString(),
         'sdk': expextedSkd,
         'trace': context.toJson(),
         'dsn': fakeDsn,
+        'sent_at': formatDateAsIso8601WithMillisPrecision(timestamp),
       };
       expect(sut.toJson(), expected);
     });