Recalculate room name on loading members (#5158)

* Recalculate room name on loading members

Because if it's a DM room, loading members might change the room name

* Swap other userA / userB constants

* Typo

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

---------

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

Author: dbkr

spec/unit/room.spec.ts

@@ -2103,7 +2103,7 @@ describe("Room", function () {
         }
 
         const memberEvent = utils.mkMembership({
-            user: "@user_a:bar",
+            user: userA,
             mship: KnownMembership.Join,
             room: roomId,
             event: true,
@@ -2114,7 +2114,7 @@ describe("Room", function () {
             const client = createClientMock([memberEvent]);
             const room = new Room(roomId, client as any, null!, { lazyLoadMembers: true });
             await room.loadMembersIfNeeded();
-            const memberA = room.getMember("@user_a:bar")!;
+            const memberA = room.getMember(userA)!;
             expect(memberA.name).toEqual("User A");
             const storedMembers = client.store.storedMembers!;
             expect(storedMembers.length).toEqual(1);
@@ -2123,7 +2123,7 @@ describe("Room", function () {
 
         it("should take members from storage if available", async function () {
             const memberEvent2 = utils.mkMembership({
-                user: "@user_a:bar",
+                user: userA,
                 mship: KnownMembership.Join,
                 room: roomId,
                 event: true,
@@ -2134,7 +2134,7 @@ describe("Room", function () {
 
             await room.loadMembersIfNeeded();
 
-            const memberA = room.getMember("@user_a:bar")!;
+            const memberA = room.getMember(userA)!;
             expect(memberA.name).toEqual("User A");
         });
 
@@ -2145,9 +2145,26 @@ describe("Room", function () {
 
             client.members.mockReturnValue({ chunk: [memberEvent] });
             await room.loadMembersIfNeeded();
-            const memberA = room.getMember("@user_a:bar")!;
+            const memberA = room.getMember(userA)!;
             expect(memberA.name).toEqual("User A");
         });
+
+        it("should emit room name change event if loading members causes the room name to change", async function () {
+            const otherMemberEvent = utils.mkMembership({
+                user: userB,
+                mship: KnownMembership.Join,
+                room: roomId,
+                event: true,
+                name: "User B",
+            });
+
+            const client = createClientMock([memberEvent, otherMemberEvent]);
+            const room = new Room(roomId, client as any, userA, { lazyLoadMembers: true });
+
+            expect(room.name).toEqual("!foo:bar");
+            await room.loadMembersIfNeeded();
+            expect(room.name).toEqual("User B");
+        });
     });
 
     describe("getMyMembership", function () {

src/models/room.ts

@@ -1103,6 +1103,8 @@ export class Room extends ReadReceipt<RoomEmittedEvents, RoomEventHandlerMap> {
         const inMemoryUpdate = this.loadMembers()
             .then((result) => {
                 this.currentState.setOutOfBandMembers(result.memberEvents);
+                // recalculate the room name: it may have been based on members, so may have changed
+                this.recalculate();
                 return result.fromServer;
             })
             .catch((err) => {