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>

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

@@ -2281,7 +2281,9 @@ describe("MatrixClient syncing", () => {
             httpBackend!.expectedRequests = [];
         });
 
-        it("should return a room based on the room initialSync API", async () => {
+        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,
@@ -2328,7 +2330,7 @@ describe("MatrixClient syncing", () => {
                 });
                 httpBackend!.when("GET", "/events").respond(200, { chunk: [] });
 
-            const prom = client!.peekInRoom(roomOne);
+                const prom = client!.peekInRoom(roomOne, limit);
                 await httpBackend!.flushAllExpected();
                 const room = await prom;
 
@@ -2341,7 +2343,8 @@ describe("MatrixClient syncing", () => {
                 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");
             }