api [nfc]: Introduce TopicName.apiName, and use for making API requests

Author: gnprice

lib/api/model/model.dart

@@ -658,9 +658,12 @@ enum MessageFlag {
 /// The name of a Zulip topic.
 // TODO(#1250): Migrate all implicit uses as String; remove "implements String".
 extension type const TopicName(String _value) implements String {
+  /// The string this topic is identified by in the Zulip API.
+  String get apiName => _value;
+
   TopicName.fromJson(this._value);
 
-  String toJson() => _value;
+  String toJson() => apiName;
 }
 
 @JsonSerializable(fieldRename: FieldRename.snake)

lib/api/route/channels.dart

@@ -59,7 +59,7 @@ Future<void> updateUserTopicCompat(ApiConnection connection, {
     // https://zulip.com/api/mute-topic
     return connection.patch('muteTopic', (_) {}, 'users/me/subscriptions/muted_topics', {
       'stream_id': streamId,
-      'topic': RawParameter(topic),
+      'topic': RawParameter(topic.apiName),
       'op': RawParameter(op),
     });
   } else {
@@ -83,7 +83,7 @@ Future<void> updateUserTopic(ApiConnection connection, {
   assert(connection.zulipFeatureLevel! >= 170);
   return connection.post('updateUserTopic', (_) {}, 'user_topics', {
     'stream_id': streamId,
-    'topic': RawParameter(topic),
+    'topic': RawParameter(topic.apiName),
     'visibility_policy': visibilityPolicy,
   });
 }

lib/api/route/messages.dart

@@ -186,7 +186,7 @@ Future<SendMessageResult> sendMessage(
       StreamDestination() => {
         'type': RawParameter('stream'),
         'to': destination.streamId,
-        'topic': RawParameter(destination.topic),
+        'topic': RawParameter(destination.topic.apiName),
       },
       DmDestination() => {
         'type': supportsTypeDirect ? RawParameter('direct') : RawParameter('private'),
@@ -453,6 +453,6 @@ Future<void> markTopicAsRead(ApiConnection connection, {
 }) {
   return connection.post('markTopicAsRead', (_) {}, 'mark_topic_as_read', {
     'stream_id': streamId,
-    'topic_name': RawParameter(topicName),
+    'topic_name': RawParameter(topicName.apiName),
   });
 }

lib/api/route/typing.dart

@@ -17,7 +17,7 @@ Future<void> setTypingStatus(ApiConnection connection, {
         'type':  RawParameter(supportsTypeChannel ? 'channel' : 'stream'),
         if (supportsStreamId) 'stream_id': destination.streamId
         else                  'to': [destination.streamId],
-        'topic': RawParameter(destination.topic),
+        'topic': RawParameter(destination.topic.apiName),
       });
     case DmDestination():
       final supportsDirect = connection.zulipFeatureLevel! >= 174; // TODO(server-7)

test/api/model/model_checks.dart

@@ -46,6 +46,10 @@ extension MessageChecks on Subject<Message> {
   Subject<String?> get matchTopic => has((e) => e.matchTopic, 'matchTopic');
 }
 
+extension TopicNameChecks on Subject<TopicName> {
+  Subject<String> get apiName => has((x) => x.apiName, 'apiName');
+}
+
 extension StreamMessageChecks on Subject<StreamMessage> {
   Subject<String?> get displayRecipient => has((e) => e.displayRecipient, 'displayRecipient');
   Subject<TopicName> get topic => has((e) => e.topic, 'topic');

test/model/typing_status_test.dart

@@ -35,7 +35,7 @@ void checkSetTypingStatusRequests(
           'type': 'channel',
           'op': op.toJson(),
           'stream_id': narrow.streamId.toString(),
-          'topic': narrow.topic}),
+          'topic': narrow.topic.apiName}),
         DmNarrow() => conditionTypingRequest({
           'type': 'direct',
           'op': op.toJson(),