api: Add route getReadReceipts

Author: sm-sayedi

lib/api/route/messages.dart

@@ -435,3 +435,23 @@ class UpdateMessageFlagsForNarrowResult {
 
   Map<String, dynamic> toJson() => _$UpdateMessageFlagsForNarrowResultToJson(this);
 }
+
+/// https://zulip.com/api/get-read-receipts
+Future<GetReadReceiptsResult> getReadReceipts(ApiConnection connection, {
+  required int messageId,
+}) {
+  return connection.get('getReadReceipts', GetReadReceiptsResult.fromJson,
+    'messages/$messageId/read_receipts', null);
+}
+
+@JsonSerializable(fieldRename: FieldRename.snake)
+class GetReadReceiptsResult {
+  const GetReadReceiptsResult({required this.userIds});
+
+  final List<int> userIds;
+
+  factory GetReadReceiptsResult.fromJson(Map<String, dynamic> json) =>
+    _$GetReadReceiptsResultFromJson(json);
+
+  Map<String, dynamic> toJson() => _$GetReadReceiptsResultToJson(this);
+}

lib/api/route/messages.g.dart

@@ -829,4 +829,15 @@ void main() {
       });
     });
   });
+
+  test('smoke getReadReceipts', () {
+    return FakeApiConnection.with_((connection) async {
+      final response = GetReadReceiptsResult(userIds: [7, 6543, 210]);
+      connection.prepare(json: response.toJson());
+      await getReadReceipts(connection, messageId: 123321);
+      check(connection.takeRequests()).single.isA<http.Request>()
+        ..method.equals('GET')
+        ..url.path.equals('/api/v1/messages/123321/read_receipts');
+    });
+  });
 }