msglist: Remove backward-compat code for servers without includeAnchor

Fixes-partly: #1837

Author: chrisbobbe

lib/model/message_list.dart

@@ -873,12 +873,6 @@ class MessageListView with ChangeNotifier, _MessageSequence {
       numBefore: kMessageListFetchBatchSize,
       numAfter: 0,
       processResult: (result) {
-        if (result.messages.isNotEmpty
-            && result.messages.last.id == messages[0].id) {
-          // TODO(server-6): includeAnchor should make this impossible
-          result.messages.removeLast();
-        }
-
         store.reconcileMessages(result.messages);
         store.recentSenders.handleMessages(result.messages); // TODO(#824)
 
@@ -909,12 +903,6 @@ class MessageListView with ChangeNotifier, _MessageSequence {
       numBefore: 0,
       numAfter: kMessageListFetchBatchSize,
       processResult: (result) {
-        if (result.messages.isNotEmpty
-            && result.messages.first.id == messages.last.id) {
-          // TODO(server-6): includeAnchor should make this impossible
-          result.messages.removeAt(0);
-        }
-
         store.reconcileMessages(result.messages);
         store.recentSenders.handleMessages(result.messages); // TODO(#824)
 

test/example_data.dart

@@ -821,14 +821,13 @@ GetMessagesResult nearGetMessagesResult({
 /// A GetMessagesResult the server might return when we request older messages.
 GetMessagesResult olderGetMessagesResult({
   required int anchor,
-  bool foundAnchor = false, // the value if the server understood includeAnchor false
   required bool foundOldest,
   bool historyLimited = false,
   required List<Message> messages,
 }) {
   return GetMessagesResult(
     anchor: anchor,
-    foundAnchor: foundAnchor,
+    foundAnchor: false,
     foundNewest: false, // empirically always this, even when anchor happens to be latest
     foundOldest: foundOldest,
     historyLimited: historyLimited,
@@ -839,14 +838,13 @@ GetMessagesResult olderGetMessagesResult({
 /// A GetMessagesResult the server might return when we request newer messages.
 GetMessagesResult newerGetMessagesResult({
   required int anchor,
-  bool foundAnchor = false, // the value if the server understood includeAnchor false
   required bool foundNewest,
   bool historyLimited = false,
   required List<Message> messages,
 }) {
   return GetMessagesResult(
     anchor: anchor,
-    foundAnchor: foundAnchor,
+    foundAnchor: false,
     foundOldest: false,
     foundNewest: foundNewest,
     historyLimited: historyLimited,

test/model/message_list_test.dart

@@ -625,40 +625,6 @@ void main() {
       check(connection.takeRequests()).single;
     }));
 
-    test('fetchOlder handles servers not understanding includeAnchor', () async {
-      await prepare();
-      await prepareMessages(foundOldest: false,
-        messages: List.generate(100, (i) => eg.streamMessage(id: 1000 + i)));
-
-      // The old behavior is to include the anchor message regardless of includeAnchor.
-      connection.prepare(json: olderResult(
-        anchor: 1000, foundOldest: false, foundAnchor: true,
-        messages: List.generate(101, (i) => eg.streamMessage(id: 900 + i)),
-      ).toJson());
-      await model.fetchOlder();
-      checkNotified(count: 2);
-      check(model)
-        ..busyFetchingMore.isFalse()
-        ..messages.length.equals(200);
-    });
-
-    test('fetchNewer handles servers not understanding includeAnchor', () async {
-      await prepare(anchor: NumericAnchor(1000));
-      await prepareMessages(foundOldest: true, foundNewest: false,
-        messages: List.generate(101, (i) => eg.streamMessage(id: 1000 + i)));
-
-      // The old behavior is to include the anchor message regardless of includeAnchor.
-      connection.prepare(json: newerResult(
-        anchor: 1100, foundNewest: false, foundAnchor: true,
-        messages: List.generate(101, (i) => eg.streamMessage(id: 1100 + i)),
-      ).toJson());
-      await model.fetchNewer();
-      checkNotified(count: 2);
-      check(model)
-        ..busyFetchingMore.isFalse()
-        ..messages.length.equals(201);
-    });
-
     // TODO(#824): move this test
     test('fetchOlder recent senders track all the messages', () async {
       await prepare();