api: Indicate support for handling empty topics

Look for `allow_empty_topic_name` and `empty_topic_name` under "Feature
level 334" in the API Changelog to verify the affected routes:
  https://zulip.com/api/changelog

Fixes: zulip#1250

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

Diff for: lib/api/route/channels.dart

@@ -8,7 +8,10 @@ part 'channels.g.dart';
 Future<GetStreamTopicsResult> getStreamTopics(ApiConnection connection, {
   required int streamId,
 }) {
-  return connection.get('getStreamTopics', GetStreamTopicsResult.fromJson, 'users/me/$streamId/topics', {});
+  final supportsEmptyTopics = connection.zulipFeatureLevel! >= 334; // TODO(server-10)
+  return connection.get('getStreamTopics', GetStreamTopicsResult.fromJson, 'users/me/$streamId/topics', {
+    if (supportsEmptyTopics) 'allow_empty_topic_name': true,
+  });
 }
 
 @JsonSerializable(fieldRename: FieldRename.snake)

Diff for: lib/api/route/events.dart

@@ -18,6 +18,7 @@ Future<InitialSnapshot> registerQueue(ApiConnection connection) {
       'user_avatar_url_field_optional': false, // TODO(#254): turn on
       'stream_typing_notifications': true,
       'user_settings_object': true,
+      'empty_topic_name': true,
     },
   });
 }

Diff for: lib/api/route/messages.dart

@@ -59,8 +59,10 @@ Future<GetMessageResult> getMessage(ApiConnection connection, {
   bool? applyMarkdown,
 }) {
   assert(connection.zulipFeatureLevel! >= 120);
+  final supportsEmptyTopics = connection.zulipFeatureLevel! >= 334; // TODO(server-10)
   return connection.get('getMessage', GetMessageResult.fromJson, 'messages/$messageId', {
     if (applyMarkdown != null) 'apply_markdown': applyMarkdown,
+    if (supportsEmptyTopics) 'allow_empty_topic_name': true,
   });
 }
 
@@ -90,6 +92,7 @@ Future<GetMessagesResult> getMessages(ApiConnection connection, {
   bool? applyMarkdown,
   // bool? useFirstUnreadAnchor // omitted because deprecated
 }) {
+  final supportsEmptyTopics = connection.zulipFeatureLevel! >= 334; // TODO(server-10)
   return connection.get('getMessages', GetMessagesResult.fromJson, 'messages', {
     'narrow': resolveDmElements(narrow, connection.zulipFeatureLevel!),
     'anchor': RawParameter(anchor.toJson()),
@@ -98,6 +101,7 @@ Future<GetMessagesResult> getMessages(ApiConnection connection, {
     'num_after': numAfter,
     if (clientGravatar != null) 'client_gravatar': clientGravatar,
     if (applyMarkdown != null) 'apply_markdown': applyMarkdown,
+    if (supportsEmptyTopics) 'allow_empty_topic_name': true,
   });
 }
 

Diff for: test/api/route/channels_test.dart

@@ -8,6 +8,30 @@ import '../../stdlib_checks.dart';
 import '../fake_api.dart';
 
 void main() {
+  test('smoke getStreamTopics', () {
+    return FakeApiConnection.with_((connection) async {
+      connection.prepare(json: GetStreamTopicsResult(topics: []).toJson());
+      await getStreamTopics(connection, streamId: 1);
+      check(connection.takeRequests()).single.isA<http.Request>()
+        ..method.equals('GET')
+        ..url.path.equals('/api/v1/users/me/1/topics')
+        ..url.queryParameters.deepEquals({
+          'allow_empty_topic_name': 'true',
+        });
+    });
+  });
+
+  test('legacy: getStreamTopics when FL < 334', () {
+    return FakeApiConnection.with_(zulipFeatureLevel: 333, (connection) async {
+      connection.prepare(json: GetStreamTopicsResult(topics: []).toJson());
+      await getStreamTopics(connection, streamId: 1);
+      check(connection.takeRequests()).single.isA<http.Request>()
+        ..method.equals('GET')
+        ..url.path.equals('/api/v1/users/me/1/topics')
+        ..url.queryParameters.deepEquals({});
+    });
+  });
+
   test('smoke updateUserTopic', () {
     return FakeApiConnection.with_((connection) async {
       connection.prepare(json: {});

Diff for: test/api/route/messages_test.dart

@@ -43,6 +43,7 @@ void main() {
           ..url.path.equals('/api/v1/messages/$messageId')
           ..url.queryParameters.deepEquals({
             if (applyMarkdown != null) 'apply_markdown': applyMarkdown.toString(),
+            'allow_empty_topic_name': 'true',
           });
       }
       return result;
@@ -149,7 +150,10 @@ void main() {
         await checkGetMessage(connection,
           messageId: 1,
           applyMarkdown: true,
-          expected: {'apply_markdown': 'true'});
+          expected: {
+            'apply_markdown': 'true',
+            'allow_empty_topic_name': 'true',
+          });
       });
     });
 
@@ -159,7 +163,19 @@ void main() {
         await checkGetMessage(connection,
           messageId: 1,
           applyMarkdown: false,
-          expected: {'apply_markdown': 'false'});
+          expected: {
+            'apply_markdown': 'false',
+            'allow_empty_topic_name': 'true',
+          });
+      });
+    });
+
+    test('legacy: empty topic name not supported', () {
+      return FakeApiConnection.with_(zulipFeatureLevel: 333, (connection) async {
+        connection.prepare(json: fakeResult.toJson());
+        await checkGetMessage(connection,
+          messageId: 1,
+          expected: {});
       });
     });
 
@@ -259,6 +275,7 @@ void main() {
             'anchor': 'newest',
             'num_before': '10',
             'num_after': '20',
+            'allow_empty_topic_name': 'true',
           });
       });
     });
@@ -292,6 +309,22 @@ void main() {
             'anchor': '42',
             'num_before': '10',
             'num_after': '20',
+            'allow_empty_topic_name': 'true',
+          });
+      });
+    });
+
+    test('legacy: empty topic name not supported', () {
+      return FakeApiConnection.with_(zulipFeatureLevel: 333, (connection) async {
+        connection.prepare(json: fakeResult.toJson());
+        await checkGetMessages(connection,
+          narrow: const CombinedFeedNarrow().apiEncode(),
+          anchor: AnchorCode.newest, numBefore: 10, numAfter: 20,
+          expected: {
+            'narrow': jsonEncode([]),
+            'anchor': 'newest',
+            'num_before': '10',
+            'num_after': '20',
           });
       });
     });