Add ability to choose how many timeline events to sync when peeking (#4300)

* Add ability to choose how many timeline events to sync when peeking.

* Add a test that covers the new method parameter.

* Formatting.

---------

Co-authored-by: Joel <joel.garplind+github@gmail.com>

Author: jgarplind

spec/integ/matrix-client-syncing.spec.ts

@@ -2281,67 +2281,70 @@ describe("MatrixClient syncing", () => {
             httpBackend!.expectedRequests = [];
         });
 
-        it("should return a room based on the room initialSync API", async () => {
-            httpBackend!.when("GET", `/rooms/${encodeURIComponent(roomOne)}/initialSync`).respond(200, {
-                room_id: roomOne,
-                membership: KnownMembership.Leave,
-                messages: {
-                    start: "start",
-                    end: "end",
-                    chunk: [
+        it.each([undefined, 100])(
+            "should return a room based on the room initialSync API with limit %s",
+            async (limit) => {
+                httpBackend!.when("GET", `/rooms/${encodeURIComponent(roomOne)}/initialSync`).respond(200, {
+                    room_id: roomOne,
+                    membership: KnownMembership.Leave,
+                    messages: {
+                        start: "start",
+                        end: "end",
+                        chunk: [
+                            {
+                                content: { body: "Message 1" },
+                                type: "m.room.message",
+                                event_id: "$eventId1",
+                                sender: userA,
+                                origin_server_ts: 12313525,
+                                room_id: roomOne,
+                            },
+                            {
+                                content: { body: "Message 2" },
+                                type: "m.room.message",
+                                event_id: "$eventId2",
+                                sender: userB,
+                                origin_server_ts: 12315625,
+                                room_id: roomOne,
+                            },
+                        ],
+                    },
+                    state: [
                         {
-                            content: { body: "Message 1" },
-                            type: "m.room.message",
-                            event_id: "$eventId1",
+                            content: { name: "Room Name" },
+                            type: "m.room.name",
+                            event_id: "$eventId",
                             sender: userA,
-                            origin_server_ts: 12313525,
+                            origin_server_ts: 12314525,
+                            state_key: "",
                             room_id: roomOne,
                         },
+                    ],
+                    presence: [
                         {
-                            content: { body: "Message 2" },
-                            type: "m.room.message",
-                            event_id: "$eventId2",
-                            sender: userB,
-                            origin_server_ts: 12315625,
-                            room_id: roomOne,
+                            content: {},
+                            type: "m.presence",
+                            sender: userA,
                         },
                     ],
-                },
-                state: [
-                    {
-                        content: { name: "Room Name" },
-                        type: "m.room.name",
-                        event_id: "$eventId",
-                        sender: userA,
-                        origin_server_ts: 12314525,
-                        state_key: "",
-                        room_id: roomOne,
-                    },
-                ],
-                presence: [
-                    {
-                        content: {},
-                        type: "m.presence",
-                        sender: userA,
-                    },
-                ],
-            });
-            httpBackend!.when("GET", "/events").respond(200, { chunk: [] });
-
-            const prom = client!.peekInRoom(roomOne);
-            await httpBackend!.flushAllExpected();
-            const room = await prom;
-
-            expect(room.roomId).toBe(roomOne);
-            expect(room.getMyMembership()).toBe(KnownMembership.Leave);
-            expect(room.name).toBe("Room Name");
-            expect(room.currentState.getStateEvents("m.room.name", "")?.getId()).toBe("$eventId");
-            expect(room.timeline[0].getContent().body).toBe("Message 1");
-            expect(room.timeline[1].getContent().body).toBe("Message 2");
-            client?.stopPeeking();
-            httpBackend!.when("GET", "/events").respond(200, { chunk: [] });
-            await httpBackend!.flushAllExpected();
-        });
+                });
+                httpBackend!.when("GET", "/events").respond(200, { chunk: [] });
+
+                const prom = client!.peekInRoom(roomOne, limit);
+                await httpBackend!.flushAllExpected();
+                const room = await prom;
+
+                expect(room.roomId).toBe(roomOne);
+                expect(room.getMyMembership()).toBe(KnownMembership.Leave);
+                expect(room.name).toBe("Room Name");
+                expect(room.currentState.getStateEvents("m.room.name", "")?.getId()).toBe("$eventId");
+                expect(room.timeline[0].getContent().body).toBe("Message 1");
+                expect(room.timeline[1].getContent().body).toBe("Message 2");
+                client?.stopPeeking();
+                httpBackend!.when("GET", "/events").respond(200, { chunk: [] });
+                await httpBackend!.flushAllExpected();
+            },
+        );
     });
 
     describe("user account data", () => {

src/client.ts

@@ -6603,13 +6603,14 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * Peek into a room and receive updates about the room. This only works if the
      * history visibility for the room is world_readable.
      * @param roomId - The room to attempt to peek into.
+     * @param limit - The number of timeline events to initially retrieve.
      * @returns Promise which resolves: Room object
      * @returns Rejects: with an error response.
      */
-    public peekInRoom(roomId: string): Promise<Room> {
+    public peekInRoom(roomId: string, limit: number = 20): Promise<Room> {
         this.peekSync?.stopPeeking();
         this.peekSync = new SyncApi(this, this.clientOpts, this.buildSyncApiOptions());
-        return this.peekSync.peek(roomId);
+        return this.peekSync.peek(roomId, limit);
     }
 
     /**

src/sync.ts

@@ -401,17 +401,18 @@ export class SyncApi {
      * Peek into a room. This will result in the room in question being synced so it
      * is accessible via getRooms(). Live updates for the room will be provided.
      * @param roomId - The room ID to peek into.
+     * @param limit - The number of timeline events to initially retrieve.
      * @returns A promise which resolves once the room has been added to the
      * store.
      */
-    public peek(roomId: string): Promise<Room> {
+    public peek(roomId: string, limit: number = 20): Promise<Room> {
         if (this._peekRoom?.roomId === roomId) {
             return Promise.resolve(this._peekRoom);
         }
 
         const client = this.client;
         this._peekRoom = this.createRoom(roomId);
-        return this.client.roomInitialSync(roomId, 20).then((response) => {
+        return this.client.roomInitialSync(roomId, limit).then((response) => {
             if (this._peekRoom?.roomId !== roomId) {
                 throw new Error("Peeking aborted");
             }