autocomplete test: Highlight one end-to-end test, cut the others

It's good to have an end-to-end test here that the actual autocomplete
results reflect the sorting that's tested by all the unit tests in the
rest of this file: a test that makes a MentionAutocompleteView, then
gives it a query, and inspects the results.

The several such test cases that were here, though, don't exercise any
distinct scenarios when it comes to that end-to-end logic; they differ
from each other only in ways that are exercised by the unit tests
above, plus the tests for RecentSenders and RecentDmConversations that
check those data structures' handling of events.  So pick just one of
these test cases and cut the rest.

Author: gnprice

test/model/autocomplete_test.dart

@@ -574,14 +574,13 @@ void main() {
       });
     });
 
-    group('autocomplete suggests relevant users in the intended order', () {
+    test('final results end-to-end', () async {
       // The order should be:
       // 1. Users most recent in the current topic/stream.
       // 2. Users most recent in the DM conversations.
 
       final stream = eg.stream();
       const topic = 'topic';
-      final streamNarrow = StreamNarrow(stream.streamId);
       final topicNarrow = TopicNarrow(stream.streamId, topic);
 
       final users = List.generate(5, (i) => eg.user(userId: i));
@@ -618,65 +617,31 @@ void main() {
         check(results).deepEquals(expected);
       }
 
-      group('StreamNarrow & TopicNarrow', () {
-        late FakeApiConnection connection;
-        late MessageListView messageList;
-
-        Future<void> fetchInitialMessagesIn(Narrow narrow) async {
-          connection = store.connection as FakeApiConnection;
-          connection.prepare(json: newestResult(
-            foundOldest: false,
-            messages: narrow is StreamNarrow
-              ? messages
-              : messages.where((m) => m.topic == topic).toList(),
-          ).toJson());
-          messageList = MessageListView.init(store: store, narrow: narrow);
-          await messageList.fetchInitial();
-        }
-
-        Future<void> checkInitialResultsIn(Narrow narrow,
-            {required List<int> expected, bool includeStream = false}) async {
-          assert(narrow is! StreamNarrow || !includeStream);
-          await prepareStore(includeMessageHistory: includeStream);
-          await fetchInitialMessagesIn(narrow);
-          await checkResultsIn(narrow, expected: expected);
-        }
-
-        test('StreamNarrow', () async {
-          await checkInitialResultsIn(streamNarrow, expected: [4, 0, 3, 1, 2]);
-        });
-
-        test('StreamNarrow, new message arrives', () async {
-          await checkInitialResultsIn(streamNarrow, expected: [4, 0, 3, 1, 2]);
-
-          // Until now, latest message id in [stream] is 60.
-          await store.addMessage(streamMessage(id: 70, senderId: 2));
-
-          await checkResultsIn(streamNarrow, expected: [2, 4, 0, 3, 1]);
-        });
-
-        test('StreamNarrow, a batch of older messages arrives', () async {
-          await checkInitialResultsIn(streamNarrow, expected: [4, 0, 3, 1, 2]);
-
-          // Until now, oldest message id in [stream] is 50.
-          final oldMessages = [
-            streamMessage(id: 30, senderId: 1),
-            streamMessage(id: 40, senderId: 2),
-          ];
-          connection.prepare(json: olderResult(
-            anchor: 50, foundOldest: false,
-            messages: oldMessages,
-          ).toJson());
-          await messageList.fetchOlder();
+      late FakeApiConnection connection;
+      late MessageListView messageList;
+
+      Future<void> fetchInitialMessagesIn(Narrow narrow) async {
+        connection = store.connection as FakeApiConnection;
+        connection.prepare(json: newestResult(
+          foundOldest: false,
+          messages: narrow is StreamNarrow
+            ? messages
+            : messages.where((m) => m.topic == topic).toList(),
+        ).toJson());
+        messageList = MessageListView.init(store: store, narrow: narrow);
+        await messageList.fetchInitial();
+      }
 
-          await checkResultsIn(streamNarrow, expected: [4, 0, 2, 1, 3]);
-        });
+      Future<void> checkInitialResultsIn(Narrow narrow,
+          {required List<int> expected, bool includeStream = false}) async {
+        assert(narrow is! StreamNarrow || !includeStream);
+        await prepareStore(includeMessageHistory: includeStream);
+        await fetchInitialMessagesIn(narrow);
+        await checkResultsIn(narrow, expected: expected);
+      }
 
-        test('TopicNarrow, other messages are in stream', () async {
-          await checkInitialResultsIn(topicNarrow, expected: [0, 4, 3, 1, 2],
-            includeStream: true);
-        });
-      });
+      await checkInitialResultsIn(topicNarrow, expected: [0, 4, 3, 1, 2],
+        includeStream: true);
     });
   });
 }