msglist test [nfc]: Make a group for MessageEvent tests

We move this to match the relative location of `handleMessageEvent`.

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

Author: PIG208

test/model/message_list_test.dart

@@ -275,42 +275,6 @@ void main() {
       [...initialMessages, ...oldMessages]);
   });
 
-  test('MessageEvent', () async {
-    final stream = eg.stream();
-    await prepare(narrow: ChannelNarrow(stream.streamId));
-    await prepareMessages(foundOldest: true, messages:
-      List.generate(30, (i) => eg.streamMessage(stream: stream)));
-
-    check(model).messages.length.equals(30);
-    await store.handleEvent(MessageEvent(id: 0,
-      message: eg.streamMessage(stream: stream)));
-    checkNotifiedOnce();
-    check(model).messages.length.equals(31);
-  });
-
-  test('MessageEvent, not in narrow', () async {
-    final stream = eg.stream();
-    await prepare(narrow: ChannelNarrow(stream.streamId));
-    await prepareMessages(foundOldest: true, messages:
-      List.generate(30, (i) => eg.streamMessage(stream: stream)));
-
-    check(model).messages.length.equals(30);
-    final otherStream = eg.stream();
-    await store.handleEvent(MessageEvent(id: 0,
-      message: eg.streamMessage(stream: otherStream)));
-    checkNotNotified();
-    check(model).messages.length.equals(30);
-  });
-
-  test('MessageEvent, before fetch', () async {
-    final stream = eg.stream();
-    await prepare(narrow: ChannelNarrow(stream.streamId));
-    await store.handleEvent(MessageEvent(id: 0,
-      message: eg.streamMessage(stream: stream)));
-    checkNotNotified();
-    check(model).fetched.isFalse();
-  });
-
   group('UserTopicEvent', () {
     // The ChannelStore.willChangeIfTopicVisible/InStream methods have their own
     // thorough unit tests.  So these tests focus on the rest of the logic.
@@ -606,6 +570,44 @@ void main() {
     });
   });
 
+  group('MessageEvent', () {
+    test('in narrow', () async {
+      final stream = eg.stream();
+      await prepare(narrow: ChannelNarrow(stream.streamId));
+      await prepareMessages(foundOldest: true, messages:
+        List.generate(30, (i) => eg.streamMessage(stream: stream)));
+
+      check(model).messages.length.equals(30);
+      await store.handleEvent(MessageEvent(id: 0,
+        message: eg.streamMessage(stream: stream)));
+      checkNotifiedOnce();
+      check(model).messages.length.equals(31);
+    });
+
+    test('not in narrow', () async {
+      final stream = eg.stream();
+      await prepare(narrow: ChannelNarrow(stream.streamId));
+      await prepareMessages(foundOldest: true, messages:
+        List.generate(30, (i) => eg.streamMessage(stream: stream)));
+
+      check(model).messages.length.equals(30);
+      final otherStream = eg.stream();
+      await store.handleEvent(MessageEvent(id: 0,
+        message: eg.streamMessage(stream: otherStream)));
+      checkNotNotified();
+      check(model).messages.length.equals(30);
+    });
+
+    test('before fetch', () async {
+      final stream = eg.stream();
+      await prepare(narrow: ChannelNarrow(stream.streamId));
+      await store.handleEvent(MessageEvent(id: 0,
+        message: eg.streamMessage(stream: stream)));
+      checkNotNotified();
+      check(model).fetched.isFalse();
+    });
+  });
+
   group('messageContentChanged', () {
     test('message present', () async {
       await prepare(narrow: const CombinedFeedNarrow());