internal_link: Parse topic permalinks

These links (`/with/NNNN`) are just accepted and ignored in this PR,
they will be interpreted in #683.

Fixes: #684

Author: sm-sayedi

lib/model/internal_link.dart

@@ -178,8 +178,9 @@ Narrow? _interpretNarrowSegments(List<String> segments, PerAccountStore store) {
         if (dmIds == null) return null;
         dmElement = ApiNarrowDm(dmIds, negated: negated);
 
-      case _NarrowOperator.near:
-        continue; // TODO(#82): support for near
+      case _NarrowOperator.near: // TODO(#82): support for near
+      case _NarrowOperator.With: // TODO(#683): support for with
+        continue;
 
       case _NarrowOperator.unknown:
         return null;
@@ -205,6 +206,9 @@ enum _NarrowOperator {
   // 'dm' is new in server-7.0; means the same as 'pm-with'
   dm,
   near,
+  // cannot use lowerCamelCase `with` as it is a reserved keyword in Dart
+  // ignore: constant_identifier_names
+  With,
   pmWith,
   stream,
   subject,

lib/model/internal_link.g.dart

@@ -161,9 +161,12 @@ void main() {
       const testCases = [
         ('/#narrow/stream/check/topic/test',                 TopicNarrow(1, 'test')),
         ('/#narrow/stream/mobile/subject/topic/near/378333', TopicNarrow(3, 'topic')),
+        ('/#narrow/stream/mobile/subject/topic/with/1',      TopicNarrow(3, 'topic')),
         ('/#narrow/stream/mobile/topic/topic/',              TopicNarrow(3, 'topic')),
         ('/#narrow/stream/stream/topic/topic/near/1',        TopicNarrow(5, 'topic')),
+        ('/#narrow/stream/stream/topic/topic/with/22',       TopicNarrow(5, 'topic')),
         ('/#narrow/stream/stream/subject/topic/near/1',      TopicNarrow(5, 'topic')),
+        ('/#narrow/stream/stream/subject/topic/with/333',    TopicNarrow(5, 'topic')),
         ('/#narrow/stream/stream/subject/topic',             TopicNarrow(5, 'topic')),
       ];
       testExpectedNarrows(testCases, streams: streams);
@@ -175,7 +178,9 @@ void main() {
       final testCases = [
         ('/#narrow/dm/1,2-group',                        expectedNarrow),
         ('/#narrow/dm/1,2-group/near/1',                 expectedNarrow),
+        ('/#narrow/dm/1,2-group/with/2',                 expectedNarrow),
         ('/#narrow/dm/a.40b.2Ecom.2Ec.2Ed.2Ecom/near/3', null),
+        ('/#narrow/dm/a.40b.2Ecom.2Ec.2Ed.2Ecom/with/4', null),
       ];
       testExpectedNarrows(testCases, streams: streams);
     });
@@ -186,7 +191,9 @@ void main() {
       final testCases = [
         ('/#narrow/pm-with/1,2-group',                        expectedNarrow),
         ('/#narrow/pm-with/1,2-group/near/1',                 expectedNarrow),
+        ('/#narrow/pm-with/1,2-group/with/2',                 expectedNarrow),
         ('/#narrow/pm-with/a.40b.2Ecom.2Ec.2Ed.2Ecom/near/3', null),
+        ('/#narrow/pm-with/a.40b.2Ecom.2Ec.2Ed.2Ecom/with/3', null),
       ];
       testExpectedNarrows(testCases, streams: streams);
     });